/**
 * @file
 * Sockets BSD-Like API module
 *
 * @defgroup socket Socket API
 * @ingroup sequential_api
 * BSD-style socket API.\n
 * Thread-safe, to be called from non-TCPIP threads only.\n
 * Can be activated by defining @ref LWIP_SOCKET to 1.\n
 * Header is in posix/sys/socket.h\b
 */

/*
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Adam Dunkels <adam@sics.se>
 *
 * Improved by Marc Boucher <marc@mbsi.ca> and David Haas <dhaas@alum.rpi.edu>
 *
 */

#include "lwip/opt.h"

#if LWIP_SOCKET /* don't build if not configured for use in lwipopts.h */

#include "lwip/sockets.h"
#include "lwip/api.h"
#include "lwip/sys.h"
#include "lwip/igmp.h"
#include "lwip/inet.h"
#include "lwip/tcp.h"
#include "lwip/raw.h"
#include "lwip/udp.h"
#include "lwip/memp.h"
#include "lwip/pbuf.h"
#include "lwip/priv/tcpip_priv.h"
#if LWIP_CHECKSUM_ON_COPY
	#include "lwip/inet_chksum.h"
#endif

#include <string.h>

/* If the netconn API is not required publicly, then we include the necessary
   files here to get the implementation */
#if !LWIP_NETCONN
	#undef LWIP_NETCONN
	#define LWIP_NETCONN 1
	#include "api_msg.c"
	#include "api_lib.c"
	#include "netbuf.c"
	#undef LWIP_NETCONN
	#define LWIP_NETCONN 0
#endif

#if LWIP_IPV4
#define IP4ADDR_PORT_TO_SOCKADDR(sin, ipaddr, port) do { \
      (sin)->sin_len = sizeof(struct sockaddr_in); \
      (sin)->sin_family = AF_INET; \
      (sin)->sin_port = lwip_htons((port)); \
      inet_addr_from_ip4addr(&(sin)->sin_addr, ipaddr); \
      memset((sin)->sin_zero, 0, SIN_ZERO_LEN); }while(0)
#define SOCKADDR4_TO_IP4ADDR_PORT(sin, ipaddr, port) do { \
    inet_addr_to_ip4addr(ip_2_ip4(ipaddr), &((sin)->sin_addr)); \
    (port) = lwip_ntohs((sin)->sin_port); }while(0)
#endif /* LWIP_IPV4 */

#if LWIP_IPV6
#define IP6ADDR_PORT_TO_SOCKADDR(sin6, ipaddr, port) do { \
      (sin6)->sin6_len = sizeof(struct sockaddr_in6); \
      (sin6)->sin6_family = AF_INET6; \
      (sin6)->sin6_port = lwip_htons((port)); \
      (sin6)->sin6_flowinfo = 0; \
      inet6_addr_from_ip6addr(&(sin6)->sin6_addr, ipaddr); \
      (sin6)->sin6_scope_id = 0; }while(0)
#define SOCKADDR6_TO_IP6ADDR_PORT(sin6, ipaddr, port) do { \
    inet6_addr_to_ip6addr(ip_2_ip6(ipaddr), &((sin6)->sin6_addr)); \
    (port) = lwip_ntohs((sin6)->sin6_port); }while(0)
#endif /* LWIP_IPV6 */

#if LWIP_IPV4 && LWIP_IPV6
static void sockaddr_to_ipaddr_port(const struct sockaddr* sockaddr, ip_addr_t* ipaddr, u16_t* port);

#define IS_SOCK_ADDR_LEN_VALID(namelen)  (((namelen) == sizeof(struct sockaddr_in)) || \
                                         ((namelen) == sizeof(struct sockaddr_in6)))
#define IS_SOCK_ADDR_TYPE_VALID(name)    (((name)->sa_family == AF_INET) || \
                                         ((name)->sa_family == AF_INET6))
#define SOCK_ADDR_TYPE_MATCH(name, sock) \
       ((((name)->sa_family == AF_INET) && !(NETCONNTYPE_ISIPV6((sock)->conn->type))) || \
       (((name)->sa_family == AF_INET6) && (NETCONNTYPE_ISIPV6((sock)->conn->type))))
#define IPADDR_PORT_TO_SOCKADDR(sockaddr, ipaddr, port) do { \
    if (IP_IS_V6(ipaddr)) { \
      IP6ADDR_PORT_TO_SOCKADDR((struct sockaddr_in6*)(void*)(sockaddr), ip_2_ip6(ipaddr), port); \
    } else { \
      IP4ADDR_PORT_TO_SOCKADDR((struct sockaddr_in*)(void*)(sockaddr), ip_2_ip4(ipaddr), port); \
    } } while(0)
#define SOCKADDR_TO_IPADDR_PORT(sockaddr, ipaddr, port) sockaddr_to_ipaddr_port(sockaddr, ipaddr, &(port))
#define DOMAIN_TO_NETCONN_TYPE(domain, type) (((domain) == AF_INET) ? \
  (type) : (enum netconn_type)((type) | NETCONN_TYPE_IPV6))
#elif LWIP_IPV6 /* LWIP_IPV4 && LWIP_IPV6 */
#define IS_SOCK_ADDR_LEN_VALID(namelen)  ((namelen) == sizeof(struct sockaddr_in6))
#define IS_SOCK_ADDR_TYPE_VALID(name)    ((name)->sa_family == AF_INET6)
#define SOCK_ADDR_TYPE_MATCH(name, sock) 1
#define IPADDR_PORT_TO_SOCKADDR(sockaddr, ipaddr, port) \
        IP6ADDR_PORT_TO_SOCKADDR((struct sockaddr_in6*)(void*)(sockaddr), ip_2_ip6(ipaddr), port)
#define SOCKADDR_TO_IPADDR_PORT(sockaddr, ipaddr, port) \
        SOCKADDR6_TO_IP6ADDR_PORT((const struct sockaddr_in6*)(const void*)(sockaddr), ipaddr, port)
#define DOMAIN_TO_NETCONN_TYPE(domain, netconn_type) (netconn_type)
#else /*-> LWIP_IPV4: LWIP_IPV4 && LWIP_IPV6 */
#define IS_SOCK_ADDR_LEN_VALID(namelen)  ((namelen) == sizeof(struct sockaddr_in))
#define IS_SOCK_ADDR_TYPE_VALID(name)    ((name)->sa_family == AF_INET)
#define SOCK_ADDR_TYPE_MATCH(name, sock) 1
#define IPADDR_PORT_TO_SOCKADDR(sockaddr, ipaddr, port) \
        IP4ADDR_PORT_TO_SOCKADDR((struct sockaddr_in*)(void*)(sockaddr), ip_2_ip4(ipaddr), port)
#define SOCKADDR_TO_IPADDR_PORT(sockaddr, ipaddr, port) \
        SOCKADDR4_TO_IP4ADDR_PORT((const struct sockaddr_in*)(const void*)(sockaddr), ipaddr, port)
#define DOMAIN_TO_NETCONN_TYPE(domain, netconn_type) (netconn_type)
#endif /* LWIP_IPV6 */

#define IS_SOCK_ADDR_TYPE_VALID_OR_UNSPEC(name)    (((name)->sa_family == AF_UNSPEC) || \
                                                    IS_SOCK_ADDR_TYPE_VALID(name))
#define SOCK_ADDR_TYPE_MATCH_OR_UNSPEC(name, sock) (((name)->sa_family == AF_UNSPEC) || \
                                                    SOCK_ADDR_TYPE_MATCH(name, sock))
#define IS_SOCK_ADDR_ALIGNED(name)      ((((mem_ptr_t)(name)) % 4) == 0)


#define LWIP_SOCKOPT_CHECK_OPTLEN(optlen, opttype) do { if ((optlen) < sizeof(opttype)) { return EINVAL; }}while(0)
#define LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, optlen, opttype) do { \
  LWIP_SOCKOPT_CHECK_OPTLEN(optlen, opttype); \
  if ((sock)->conn == NULL) { return EINVAL; } }while(0)
#define LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, optlen, opttype) do { \
  LWIP_SOCKOPT_CHECK_OPTLEN(optlen, opttype); \
  if (((sock)->conn == NULL) || ((sock)->conn->pcb.tcp == NULL)) { return EINVAL; } }while(0)
#define LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, opttype, netconntype) do { \
  LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, optlen, opttype); \
  if (NETCONNTYPE_GROUP(netconn_type((sock)->conn)) != netconntype) { return ENOPROTOOPT; } }while(0)


#define LWIP_SETGETSOCKOPT_DATA_VAR_REF(name)     API_VAR_REF(name)
#define LWIP_SETGETSOCKOPT_DATA_VAR_DECLARE(name) API_VAR_DECLARE(struct lwip_setgetsockopt_data, name)
#define LWIP_SETGETSOCKOPT_DATA_VAR_FREE(name)    API_VAR_FREE(MEMP_SOCKET_SETGETSOCKOPT_DATA, name)
#if LWIP_MPU_COMPATIBLE
#define LWIP_SETGETSOCKOPT_DATA_VAR_ALLOC(name, sock) do { \
  name = (struct lwip_setgetsockopt_data *)memp_malloc(MEMP_SOCKET_SETGETSOCKOPT_DATA); \
  if (name == NULL) { \
    sock_set_errno(sock, ENOMEM); \
    return -1; \
  } }while(0)
#else /* LWIP_MPU_COMPATIBLE */
#define LWIP_SETGETSOCKOPT_DATA_VAR_ALLOC(name, sock)
#endif /* LWIP_MPU_COMPATIBLE */

#if LWIP_SO_SNDRCVTIMEO_NONSTANDARD
#define LWIP_SO_SNDRCVTIMEO_OPTTYPE int
#define LWIP_SO_SNDRCVTIMEO_SET(optval, val) (*(int *)(optval) = (val))
#define LWIP_SO_SNDRCVTIMEO_GET_MS(optval)   ((s32_t)*(const int*)(optval))
#else
#define LWIP_SO_SNDRCVTIMEO_OPTTYPE struct timeval
#define LWIP_SO_SNDRCVTIMEO_SET(optval, val)  do { \
  s32_t loc = (val); \
  ((struct timeval *)(optval))->tv_sec = (loc) / 1000U; \
  ((struct timeval *)(optval))->tv_usec = ((loc) % 1000U) * 1000U; }while(0)
#define LWIP_SO_SNDRCVTIMEO_GET_MS(optval) ((((const struct timeval *)(optval))->tv_sec * 1000U) + (((const struct timeval *)(optval))->tv_usec / 1000U))
#endif

#define NUM_SOCKETS MEMP_NUM_NETCONN

/** This is overridable for the rare case where more than 255 threads
 * select on the same socket...
 */
#ifndef SELWAIT_T
	#define SELWAIT_T u8_t
#endif

#include <rtthread.h>
#ifdef RT_USING_DFS_NET
	#include <ipc/waitqueue.h>
#endif

/** Contains all internal pointers and states used for a socket */
struct lwip_sock {
	/** sockets currently are built on netconns, each socket has one netconn */
	struct netconn* conn;
	/** data that was left from the previous read */
	void* lastdata;
	/** offset in the data that was left from the previous read */
	u16_t lastoffset;
	/** number of times data was received, set by event_callback(),
	    tested by the receive and select functions */
	s16_t rcvevent;
	/** number of times data was ACKed (free send buffer), set by event_callback(),
	    tested by select */
	u16_t sendevent;
	/** error happened for this socket, set by event_callback(), tested by select */
	u16_t errevent;
	/** last error that occurred on this socket (in fact, all our errnos fit into an u8_t) */
	u8_t err;
	/** counter of how many threads are waiting for this socket using select */
	SELWAIT_T select_waiting;

#ifdef RT_USING_DFS_NET
	rt_wqueue_t wait_head;
#endif
};

#if LWIP_NETCONN_SEM_PER_THREAD
	#define SELECT_SEM_T        sys_sem_t*
	#define SELECT_SEM_PTR(sem) (sem)
#else /* LWIP_NETCONN_SEM_PER_THREAD */
	#define SELECT_SEM_T        sys_sem_t
	#define SELECT_SEM_PTR(sem) (&(sem))
#endif /* LWIP_NETCONN_SEM_PER_THREAD */

/** Description for a task waiting in select */
struct lwip_select_cb {
	/** Pointer to the next waiting task */
	struct lwip_select_cb* next;
	/** Pointer to the previous waiting task */
	struct lwip_select_cb* prev;
	/** readset passed to select */
	fd_set* readset;
	/** writeset passed to select */
	fd_set* writeset;
	/** unimplemented: exceptset passed to select */
	fd_set* exceptset;
	/** don't signal the same semaphore twice: set to 1 when signalled */
	int sem_signalled;
	/** semaphore to wake up a task waiting for select */
	SELECT_SEM_T sem;
};

/** A struct sockaddr replacement that has the same alignment as sockaddr_in/
 *  sockaddr_in6 if instantiated.
 */
union sockaddr_aligned {
	struct sockaddr sa;
#if LWIP_IPV6
	struct sockaddr_in6 sin6;
#endif /* LWIP_IPV6 */
#if LWIP_IPV4
	struct sockaddr_in sin;
#endif /* LWIP_IPV4 */
};

#if LWIP_IGMP
/* Define the number of IPv4 multicast memberships, default is one per socket */
#ifndef LWIP_SOCKET_MAX_MEMBERSHIPS
	#define LWIP_SOCKET_MAX_MEMBERSHIPS NUM_SOCKETS
#endif

/* This is to keep track of IP_ADD_MEMBERSHIP calls to drop the membership when
   a socket is closed */
struct lwip_socket_multicast_pair {
	/** the socket */
	struct lwip_sock* sock;
	/** the interface address */
	ip4_addr_t if_addr;
	/** the group address */
	ip4_addr_t multi_addr;
};

struct lwip_socket_multicast_pair socket_ipv4_multicast_memberships[LWIP_SOCKET_MAX_MEMBERSHIPS];

static int  lwip_socket_register_membership(int s, const ip4_addr_t* if_addr, const ip4_addr_t* multi_addr);
static void lwip_socket_unregister_membership(int s, const ip4_addr_t* if_addr, const ip4_addr_t* multi_addr);
static void lwip_socket_drop_registered_memberships(int s);
#endif /* LWIP_IGMP */

/** The global array of available sockets */
static struct lwip_sock sockets[NUM_SOCKETS];
/** The global list of tasks waiting for select */
static struct lwip_select_cb* select_cb_list;
/** This counter is increased from lwip_select when the list is changed
    and checked in event_callback to see if it has changed. */
static volatile int select_cb_ctr;

#if LWIP_SOCKET_SET_ERRNO
	#ifndef set_errno
		#define set_errno(err) do { if (err) { errno = (err); } } while(0)
	#endif
#else /* LWIP_SOCKET_SET_ERRNO */
	#define set_errno(err)
#endif /* LWIP_SOCKET_SET_ERRNO */

#define sock_set_errno(sk, e) do { \
  const int sockerr = (e); \
  sk->err = (u8_t)sockerr; \
  set_errno(sockerr); \
} while (0)

/* Forward declaration of some functions */
static void event_callback(struct netconn* conn, enum netconn_evt evt, u16_t len);
#if !LWIP_TCPIP_CORE_LOCKING
	static void lwip_getsockopt_callback(void* arg);
	static void lwip_setsockopt_callback(void* arg);
#endif
static u8_t lwip_getsockopt_impl(int s, int level, int optname, void* optval, socklen_t* optlen);
static u8_t lwip_setsockopt_impl(int s, int level, int optname, const void* optval, socklen_t optlen);

#if LWIP_IPV4 && LWIP_IPV6
static void
sockaddr_to_ipaddr_port(const struct sockaddr* sockaddr, ip_addr_t* ipaddr, u16_t* port)
{
	if((sockaddr->sa_family) == AF_INET6) {
		SOCKADDR6_TO_IP6ADDR_PORT((const struct sockaddr_in6*)(const void*)(sockaddr), ipaddr, *port);
		ipaddr->type = IPADDR_TYPE_V6;
	} else {
		SOCKADDR4_TO_IP4ADDR_PORT((const struct sockaddr_in*)(const void*)(sockaddr), ipaddr, *port);
		ipaddr->type = IPADDR_TYPE_V4;
	}
}
#endif /* LWIP_IPV4 && LWIP_IPV6 */

/** LWIP_NETCONN_SEM_PER_THREAD==1: initialize thread-local semaphore */
void
lwip_socket_thread_init(void)
{
	netconn_thread_init();
}

/** LWIP_NETCONN_SEM_PER_THREAD==1: destroy thread-local semaphore */
void
lwip_socket_thread_cleanup(void)
{
	netconn_thread_cleanup();
}

/**
 * Map a externally used socket index to the internal socket representation.
 *
 * @param s externally used socket index
 * @return struct lwip_sock for the socket or NULL if not found
 */
static struct lwip_sock*
get_socket(int s)
{
	struct lwip_sock* sock;

	s -= LWIP_SOCKET_OFFSET;

	if((s < 0) || (s >= NUM_SOCKETS)) {
		LWIP_DEBUGF(SOCKETS_DEBUG, ("get_socket(%d): invalid\n", s + LWIP_SOCKET_OFFSET));
		set_errno(EBADF);
		return NULL;
	}

	sock = &sockets[s];

	if(!sock->conn) {
		LWIP_DEBUGF(SOCKETS_DEBUG, ("get_socket(%d): not active\n", s + LWIP_SOCKET_OFFSET));
		set_errno(EBADF);
		return NULL;
	}

	return sock;
}

/**
 * Same as get_socket but doesn't set errno
 *
 * @param s externally used socket index
 * @return struct lwip_sock for the socket or NULL if not found
 */
static struct lwip_sock*
tryget_socket(int s)
{
	s -= LWIP_SOCKET_OFFSET;

	if((s < 0) || (s >= NUM_SOCKETS)) {
		return NULL;
	}

	if(!sockets[s].conn) {
		return NULL;
	}

	return &sockets[s];
}

/**
 * Same as tryget_socket but a global routine.
 *
 * @param s externally used socket index
 * @return struct lwip_sock for the socket or NULL if not found
 */
struct lwip_sock*
lwip_tryget_socket(int s)
{
	return tryget_socket(s);
}



/**
 * Allocate a new socket for a given netconn.
 *
 * @param newconn the netconn for which to allocate a socket
 * @param accepted 1 if socket has been created by accept(),
 *                 0 if socket has been created by socket()
 * @return the index of the new socket; -1 on error
 */
static int
alloc_socket(struct netconn* newconn, int accepted)
{
	int i;
	SYS_ARCH_DECL_PROTECT(lev);

	/* allocate a new socket identifier */
	for(i = 0; i < NUM_SOCKETS; ++i) {
		/* Protect socket array */
		SYS_ARCH_PROTECT(lev);

		if(!sockets[i].conn && (sockets[i].select_waiting == 0)) {
			sockets[i].conn       = newconn;
			/* The socket is not yet known to anyone, so no need to protect
			   after having marked it as used. */
			SYS_ARCH_UNPROTECT(lev);
			sockets[i].lastdata   = NULL;
			sockets[i].lastoffset = 0;
			sockets[i].rcvevent   = 0;
			/* TCP sendbuf is empty, but the socket is not yet writable until connected
			 * (unless it has been created by accept()). */
			sockets[i].sendevent  = (NETCONNTYPE_GROUP(newconn->type) == NETCONN_TCP ? (accepted != 0) : 1);
			sockets[i].errevent   = 0;
			sockets[i].err        = 0;
			return i + LWIP_SOCKET_OFFSET;
		}

		SYS_ARCH_UNPROTECT(lev);
	}

	return -1;
}

/** Free a socket. The socket's netconn must have been
 * delete before!
 *
 * @param sock the socket to free
 * @param is_tcp != 0 for TCP sockets, used to free lastdata
 */
static void
free_socket(struct lwip_sock* sock, int is_tcp)
{
	void* lastdata;

	lastdata         = sock->lastdata;
	sock->lastdata   = NULL;
	sock->lastoffset = 0;
	sock->err        = 0;

	/* Protect socket array */
	SYS_ARCH_SET(sock->conn, NULL);
	/* don't use 'sock' after this line, as another task might have allocated it */

	if(lastdata != NULL) {
		if(is_tcp) {
			pbuf_free((struct pbuf*)lastdata);
		} else {
			netbuf_delete((struct netbuf*)lastdata);
		}
	}
}

/* Below this, the well-known socket functions are implemented.
 * Use google.com or opengroup.org to get a good description :-)
 *
 * Exceptions are documented!
 */

int
lwip_accept(int s, struct sockaddr* addr, socklen_t* addrlen)
{
	struct lwip_sock* sock, *nsock;
	struct netconn* newconn;
	ip_addr_t naddr;
	u16_t port = 0;
	int newsock;
	err_t err;
	SYS_ARCH_DECL_PROTECT(lev);

	LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d)...\n", s));
	sock = get_socket(s);

	if(!sock) {
		return -1;
	}

	if(netconn_is_nonblocking(sock->conn) && (sock->rcvevent <= 0)) {
		LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d): returning EWOULDBLOCK\n", s));
		set_errno(EWOULDBLOCK);
		return -1;
	}

	/* wait for a new connection */
	err = netconn_accept(sock->conn, &newconn);

	if(err != ERR_OK) {
		LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d): netconn_acept failed, err=%d\n", s, err));

		if(NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_TCP) {
			sock_set_errno(sock, EOPNOTSUPP);
		} else if(err == ERR_CLSD) {
			sock_set_errno(sock, EINVAL);
		} else {
			sock_set_errno(sock, err_to_errno(err));
		}

		return -1;
	}

	LWIP_ASSERT("newconn != NULL", newconn != NULL);

	newsock = alloc_socket(newconn, 1);

	if(newsock == -1) {
		netconn_delete(newconn);
		sock_set_errno(sock, ENFILE);
		return -1;
	}

	LWIP_ASSERT("invalid socket index", (newsock >= LWIP_SOCKET_OFFSET) && (newsock < NUM_SOCKETS + LWIP_SOCKET_OFFSET));
	// LWIP_ASSERT("newconn->callback == event_callback", newconn->callback == event_callback);
	nsock = &sockets[newsock - LWIP_SOCKET_OFFSET];

	/* See event_callback: If data comes in right away after an accept, even
	 * though the server task might not have created a new socket yet.
	 * In that case, newconn->socket is counted down (newconn->socket--),
	 * so nsock->rcvevent is >= 1 here!
	 */
	SYS_ARCH_PROTECT(lev);
	nsock->rcvevent += (s16_t)(-1 - newconn->socket);
	newconn->socket = newsock;
	SYS_ARCH_UNPROTECT(lev);

	/* Note that POSIX only requires us to check addr is non-NULL. addrlen must
	 * not be NULL if addr is valid.
	 */
	if(addr != NULL) {
		union sockaddr_aligned tempaddr;
		/* get the IP address and port of the remote host */
		err = netconn_peer(newconn, &naddr, &port);

		if(err != ERR_OK) {
			LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d): netconn_peer failed, err=%d\n", s, err));
			netconn_delete(newconn);
			free_socket(nsock, 1);
			sock_set_errno(sock, err_to_errno(err));
			return -1;
		}

		LWIP_ASSERT("addr valid but addrlen NULL", addrlen != NULL);

		IPADDR_PORT_TO_SOCKADDR(&tempaddr, &naddr, port);

		if(*addrlen > tempaddr.sa.sa_len) {
			*addrlen = tempaddr.sa.sa_len;
		}

		MEMCPY(addr, &tempaddr, *addrlen);

		LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d) returning new sock=%d addr=", s, newsock));
		ip_addr_debug_print_val(SOCKETS_DEBUG, naddr);
		LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F"\n", port));
	} else {
		LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d) returning new sock=%d", s, newsock));
	}

	sock_set_errno(sock, 0);
	return newsock;
}

int
lwip_bind(int s, const struct sockaddr* name, socklen_t namelen)
{
	struct lwip_sock* sock;
	ip_addr_t local_addr;
	u16_t local_port;
	err_t err;

	sock = get_socket(s);

	if(!sock) {
		return -1;
	}

	if(!SOCK_ADDR_TYPE_MATCH(name, sock)) {
		/* sockaddr does not match socket type (IPv4/IPv6) */
		sock_set_errno(sock, err_to_errno(ERR_VAL));
		return -1;
	}

	/* check size, family and alignment of 'name' */
	LWIP_ERROR("lwip_bind: invalid address", (IS_SOCK_ADDR_LEN_VALID(namelen) &&
	           IS_SOCK_ADDR_TYPE_VALID(name) && IS_SOCK_ADDR_ALIGNED(name)),
	           sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);
	LWIP_UNUSED_ARG(namelen);

	SOCKADDR_TO_IPADDR_PORT(name, &local_addr, local_port);
	LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_bind(%d, addr=", s));
	ip_addr_debug_print_val(SOCKETS_DEBUG, local_addr);
	LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F")\n", local_port));

#if LWIP_IPV4 && LWIP_IPV6

	/* Dual-stack: Unmap IPv4 mapped IPv6 addresses */
	if(IP_IS_V6_VAL(local_addr) && ip6_addr_isipv4mappedipv6(ip_2_ip6(&local_addr))) {
		unmap_ipv4_mapped_ipv6(ip_2_ip4(&local_addr), ip_2_ip6(&local_addr));
		IP_SET_TYPE_VAL(local_addr, IPADDR_TYPE_V4);
	}

#endif /* LWIP_IPV4 && LWIP_IPV6 */

	err = netconn_bind(sock->conn, &local_addr, local_port);

	if(err != ERR_OK) {
		LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_bind(%d) failed, err=%d\n", s, err));
		sock_set_errno(sock, err_to_errno(err));
		return -1;
	}

	LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_bind(%d) succeeded\n", s));
	sock_set_errno(sock, 0);
	return 0;
}

int
lwip_close(int s)
{
	struct lwip_sock* sock;
	int is_tcp = 0;
	err_t err;

	LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_close(%d)\n", s));

	sock = get_socket(s);

	if(!sock) {
		return -1;
	}

	if(sock->conn != NULL) {
		is_tcp = NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP;
	} else {
		LWIP_ASSERT("sock->lastdata == NULL", sock->lastdata == NULL);
	}

#if LWIP_IGMP
	/* drop all possibly joined IGMP memberships */
	lwip_socket_drop_registered_memberships(s);
#endif /* LWIP_IGMP */

	err = netconn_delete(sock->conn);

	if(err != ERR_OK) {
		sock_set_errno(sock, err_to_errno(err));
		return -1;
	}

	free_socket(sock, is_tcp);
	set_errno(0);
	return 0;
}

int
lwip_connect(int s, const struct sockaddr* name, socklen_t namelen)
{
	struct lwip_sock* sock;
	err_t err;

	sock = get_socket(s);

	if(!sock) {
		return -1;
	}

	if(!SOCK_ADDR_TYPE_MATCH_OR_UNSPEC(name, sock)) {
		/* sockaddr does not match socket type (IPv4/IPv6) */
		sock_set_errno(sock, err_to_errno(ERR_VAL));
		return -1;
	}

	LWIP_UNUSED_ARG(namelen);

	if(name->sa_family == AF_UNSPEC) {
		LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d, AF_UNSPEC)\n", s));
		err = netconn_disconnect(sock->conn);
	} else {
		ip_addr_t remote_addr;
		u16_t remote_port;

		/* check size, family and alignment of 'name' */
		LWIP_ERROR("lwip_connect: invalid address", IS_SOCK_ADDR_LEN_VALID(namelen) &&
		           IS_SOCK_ADDR_TYPE_VALID_OR_UNSPEC(name) && IS_SOCK_ADDR_ALIGNED(name),
		           sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);

		SOCKADDR_TO_IPADDR_PORT(name, &remote_addr, remote_port);
		LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d, addr=", s));
		ip_addr_debug_print_val(SOCKETS_DEBUG, remote_addr);
		LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F")\n", remote_port));

#if LWIP_IPV4 && LWIP_IPV6

		/* Dual-stack: Unmap IPv4 mapped IPv6 addresses */
		if(IP_IS_V6_VAL(remote_addr) && ip6_addr_isipv4mappedipv6(ip_2_ip6(&remote_addr))) {
			unmap_ipv4_mapped_ipv6(ip_2_ip4(&remote_addr), ip_2_ip6(&remote_addr));
			IP_SET_TYPE_VAL(remote_addr, IPADDR_TYPE_V4);
		}

#endif /* LWIP_IPV4 && LWIP_IPV6 */

		err = netconn_connect(sock->conn, &remote_addr, remote_port);
	}

	if(err != ERR_OK) {
		LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d) failed, err=%d\n", s, err));
		sock_set_errno(sock, err_to_errno(err));
		return -1;
	}

	LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d) succeeded\n", s));
	sock_set_errno(sock, 0);
	return 0;
}

/**
 * Set a socket into listen mode.
 * The socket may not have been used for another connection previously.
 *
 * @param s the socket to set to listening mode
 * @param backlog (ATTENTION: needs TCP_LISTEN_BACKLOG=1)
 * @return 0 on success, non-zero on failure
 */
int
lwip_listen(int s, int backlog)
{
	struct lwip_sock* sock;
	err_t err;

	LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_listen(%d, backlog=%d)\n", s, backlog));

	sock = get_socket(s);

	if(!sock) {
		return -1;
	}

	/* limit the "backlog" parameter to fit in an u8_t */
	backlog = LWIP_MIN(LWIP_MAX(backlog, 0), 0xff);

	err = netconn_listen_with_backlog(sock->conn, (u8_t)backlog);

	if(err != ERR_OK) {
		LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_listen(%d) failed, err=%d\n", s, err));

		if(NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_TCP) {
			sock_set_errno(sock, EOPNOTSUPP);
			return -1;
		}

		sock_set_errno(sock, err_to_errno(err));
		return -1;
	}

	sock_set_errno(sock, 0);
	return 0;
}

int
lwip_recvfrom(int s, void* mem, size_t len, int flags,
              struct sockaddr* from, socklen_t* fromlen)
{
	struct lwip_sock* sock;
	void*             buf = NULL;
	struct pbuf*      p;
	u16_t            buflen, copylen;
	int              off = 0;
	u8_t             done = 0;
	err_t            err;

	LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d, %p, %"SZT_F", 0x%x, ..)\n", s, mem, len, flags));
	sock = get_socket(s);

	if(!sock) {
		return -1;
	}

	do {
		LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: top while sock->lastdata=%p\n", sock->lastdata));

		/* Check if there is data left from the last recv operation. */
		if(sock->lastdata) {
			buf = sock->lastdata;
		} else {
			/* If this is non-blocking call, then check first */
			if(((flags & MSG_DONTWAIT) || netconn_is_nonblocking(sock->conn)) &&
			        (sock->rcvevent <= 0)) {
				if(off > 0) {
					/* already received data, return that */
					sock_set_errno(sock, 0);
					return off;
				}

				LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d): returning EWOULDBLOCK\n", s));
				set_errno(EWOULDBLOCK);
				return -1;
			}

			/* No data was left from the previous operation, so we try to get
			   some from the network. */
			if(NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) {
				err = netconn_recv_tcp_pbuf(sock->conn, (struct pbuf**)&buf);
			} else {
				err = netconn_recv(sock->conn, (struct netbuf**)&buf);
			}

			LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: netconn_recv err=%d, netbuf=%p\n",
			                            err, buf));

			if(err != ERR_OK) {
				if(off > 0) {
					if(err == ERR_CLSD) {
						/* closed but already received data, ensure select gets the FIN, too */
						event_callback(sock->conn, NETCONN_EVT_RCVPLUS, 0);
					}

					/* already received data, return that */
					sock_set_errno(sock, 0);
					return off;
				}

				/* We should really do some error checking here. */
				LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d): buf == NULL, error is \"%s\"!\n",
				                            s, lwip_strerr(err)));
				sock_set_errno(sock, err_to_errno(err));

				if(err == ERR_CLSD) {
					return 0;
				} else {
					return -1;
				}
			}

			LWIP_ASSERT("buf != NULL", buf != NULL);
			sock->lastdata = buf;
		}

		if(NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) {
			p = (struct pbuf*)buf;
		} else {
			p = ((struct netbuf*)buf)->p;
		}

		buflen = p->tot_len;
		LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: buflen=%"U16_F" len=%"SZT_F" off=%d sock->lastoffset=%"U16_F"\n",
		                            buflen, len, off, sock->lastoffset));

		buflen -= sock->lastoffset;

		if(len > buflen) {
			copylen = buflen;
		} else {
			copylen = (u16_t)len;
		}

		/* copy the contents of the received buffer into
		the supplied memory pointer mem */
		pbuf_copy_partial(p, (u8_t*)mem + off, copylen, sock->lastoffset);

		off += copylen;

		if(NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) {
			LWIP_ASSERT("invalid copylen, len would underflow", len >= copylen);
			len -= copylen;

			if((len <= 0) ||
			        (p->flags & PBUF_FLAG_PUSH) ||
			        (sock->rcvevent <= 0) ||
			        ((flags & MSG_PEEK) != 0)) {
				done = 1;
			}
		} else {
			done = 1;
		}

		/* Check to see from where the data was.*/
		if(done) {
#if !SOCKETS_DEBUG

			if(from && fromlen)
#endif /* !SOCKETS_DEBUG */
			{
				u16_t port;
				ip_addr_t tmpaddr;
				ip_addr_t* fromaddr;
				union sockaddr_aligned saddr;
				LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d): addr=", s));

				if(NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) {
					fromaddr = &tmpaddr;
					netconn_getaddr(sock->conn, fromaddr, &port, 0);
				} else {
					port = netbuf_fromport((struct netbuf*)buf);
					fromaddr = netbuf_fromaddr((struct netbuf*)buf);
				}

#if LWIP_IPV4 && LWIP_IPV6

				/* Dual-stack: Map IPv4 addresses to IPv4 mapped IPv6 */
				if(NETCONNTYPE_ISIPV6(netconn_type(sock->conn)) && IP_IS_V4(fromaddr)) {
					ip4_2_ipv4_mapped_ipv6(ip_2_ip6(fromaddr), ip_2_ip4(fromaddr));
					IP_SET_TYPE(fromaddr, IPADDR_TYPE_V6);
				}

#endif /* LWIP_IPV4 && LWIP_IPV6 */

				IPADDR_PORT_TO_SOCKADDR(&saddr, fromaddr, port);
				ip_addr_debug_print(SOCKETS_DEBUG, fromaddr);
				LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F" len=%d\n", port, off));
#if SOCKETS_DEBUG

				if(from && fromlen)
#endif /* SOCKETS_DEBUG */
				{
					if(*fromlen > saddr.sa.sa_len) {
						*fromlen = saddr.sa.sa_len;
					}

					MEMCPY(from, &saddr, *fromlen);
				}
			}
		}

		/* If we don't peek the incoming message... */
		if((flags & MSG_PEEK) == 0) {
			/* If this is a TCP socket, check if there is data left in the
			   buffer. If so, it should be saved in the sock structure for next
			   time around. */
			if((NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) && (buflen - copylen > 0)) {
				sock->lastdata = buf;
				sock->lastoffset += copylen;
				LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: lastdata now netbuf=%p\n", buf));
			} else {
				sock->lastdata = NULL;
				sock->lastoffset = 0;
				LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: deleting netbuf=%p\n", buf));

				if(NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) {
					pbuf_free((struct pbuf*)buf);
				} else {
					netbuf_delete((struct netbuf*)buf);
				}

				buf = NULL;
			}
		}
	} while(!done);

	sock_set_errno(sock, 0);
	return off;
}

int
lwip_read(int s, void* mem, size_t len)
{
	return lwip_recvfrom(s, mem, len, 0, NULL, NULL);
}

int
lwip_recv(int s, void* mem, size_t len, int flags)
{
	return lwip_recvfrom(s, mem, len, flags, NULL, NULL);
}

int
lwip_send(int s, const void* data, size_t size, int flags)
{
	struct lwip_sock* sock;
	err_t err;
	u8_t write_flags;
	size_t written;

	LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_send(%d, data=%p, size=%"SZT_F", flags=0x%x)\n",
	                            s, data, size, flags));

	sock = get_socket(s);

	if(!sock) {
		return -1;
	}

	if(NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_TCP) {
#if (LWIP_UDP || LWIP_RAW)
		return lwip_sendto(s, data, size, flags, NULL, 0);
#else /* (LWIP_UDP || LWIP_RAW) */
		sock_set_errno(sock, err_to_errno(ERR_ARG));
		return -1;
#endif /* (LWIP_UDP || LWIP_RAW) */
	}

	write_flags = NETCONN_COPY |
	              ((flags & MSG_MORE)     ? NETCONN_MORE      : 0) |
	              ((flags & MSG_DONTWAIT) ? NETCONN_DONTBLOCK : 0);
	written = 0;
	err = netconn_write_partly(sock->conn, data, size, write_flags, &written);

	LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_send(%d) err=%d written=%"SZT_F"\n", s, err, written));
	sock_set_errno(sock, err_to_errno(err));
	return (err == ERR_OK ? (int)written : -1);
}

int
lwip_sendmsg(int s, const struct msghdr* msg, int flags)
{
	struct lwip_sock* sock;
	int i;
#if LWIP_TCP
	u8_t write_flags;
	size_t written;
#endif
	int size = 0;
	err_t err = ERR_OK;

	sock = get_socket(s);

	if(!sock) {
		return -1;
	}

	LWIP_ERROR("lwip_sendmsg: invalid msghdr", msg != NULL,
	           sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);

	LWIP_UNUSED_ARG(msg->msg_control);
	LWIP_UNUSED_ARG(msg->msg_controllen);
	LWIP_UNUSED_ARG(msg->msg_flags);
	LWIP_ERROR("lwip_sendmsg: invalid msghdr iov", (msg->msg_iov != NULL && msg->msg_iovlen != 0),
	           sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);

	if(NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) {
#if LWIP_TCP
		write_flags = NETCONN_COPY |
		              ((flags & MSG_MORE)     ? NETCONN_MORE      : 0) |
		              ((flags & MSG_DONTWAIT) ? NETCONN_DONTBLOCK : 0);

		for(i = 0; i < msg->msg_iovlen; i++) {
			u8_t apiflags = write_flags;

			if(i + 1 < msg->msg_iovlen) {
				apiflags |= NETCONN_MORE;
			}

			written = 0;
			err = netconn_write_partly(sock->conn, msg->msg_iov[i].iov_base, msg->msg_iov[i].iov_len, write_flags, &written);

			if(err == ERR_OK) {
				size += written;

				/* check that the entire IO vector was accepected, if not return a partial write */
				if(written != msg->msg_iov[i].iov_len)
					break;
			}
			/* none of this IO vector was accepted, but previous was, return partial write and conceal ERR_WOULDBLOCK */
			else if(err == ERR_WOULDBLOCK && size > 0) {
				err = ERR_OK;
				/* let ERR_WOULDBLOCK persist on the netconn since we are returning ERR_OK */
				break;
			} else {
				size = -1;
				break;
			}
		}

		sock_set_errno(sock, err_to_errno(err));
		return size;
#else /* LWIP_TCP */
		sock_set_errno(sock, err_to_errno(ERR_ARG));
		return -1;
#endif /* LWIP_TCP */
	}

	/* else, UDP and RAW NETCONNs */
#if LWIP_UDP || LWIP_RAW
	{
		struct netbuf* chain_buf;

		LWIP_UNUSED_ARG(flags);
		LWIP_ERROR("lwip_sendmsg: invalid msghdr name", (((msg->msg_name == NULL) && (msg->msg_namelen == 0)) ||
		           IS_SOCK_ADDR_LEN_VALID(msg->msg_namelen)),
		           sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);

		/* initialize chain buffer with destination */
		chain_buf = netbuf_new();

		if(!chain_buf) {
			sock_set_errno(sock, err_to_errno(ERR_MEM));
			return -1;
		}

		if(msg->msg_name) {
			u16_t remote_port;
			SOCKADDR_TO_IPADDR_PORT((const struct sockaddr*)msg->msg_name, &chain_buf->addr, remote_port);
			netbuf_fromport(chain_buf) = remote_port;
		}

#if LWIP_NETIF_TX_SINGLE_PBUF

		for(i = 0; i < msg->msg_iovlen; i++) {
			size += msg->msg_iov[i].iov_len;
		}

		/* Allocate a new netbuf and copy the data into it. */
		if(netbuf_alloc(chain_buf, (u16_t)size) == NULL) {
			err = ERR_MEM;
		} else {
			/* flatten the IO vectors */
			size_t offset = 0;

			for(i = 0; i < msg->msg_iovlen; i++) {
				MEMCPY(&((u8_t*)chain_buf->p->payload)[offset], msg->msg_iov[i].iov_base, msg->msg_iov[i].iov_len);
				offset += msg->msg_iov[i].iov_len;
			}

#if LWIP_CHECKSUM_ON_COPY
			{
				/* This can be improved by using LWIP_CHKSUM_COPY() and aggregating the checksum for each IO vector */
				u16_t chksum = ~inet_chksum_pbuf(chain_buf->p);
				netbuf_set_chksum(chain_buf, chksum);
			}
#endif /* LWIP_CHECKSUM_ON_COPY */
			err = ERR_OK;
		}

#else /* LWIP_NETIF_TX_SINGLE_PBUF */

		/* create a chained netbuf from the IO vectors. NOTE: we assemble a pbuf chain
		   manually to avoid having to allocate, chain, and delete a netbuf for each iov */
		for(i = 0; i < msg->msg_iovlen; i++) {
			struct pbuf* p = pbuf_alloc(PBUF_TRANSPORT, 0, PBUF_REF);

			if(p == NULL) {
				err = ERR_MEM; /* let netbuf_delete() cleanup chain_buf */
				break;
			}

			p->payload = msg->msg_iov[i].iov_base;
			LWIP_ASSERT("iov_len < u16_t", msg->msg_iov[i].iov_len <= 0xFFFF);
			p->len = p->tot_len = (u16_t)msg->msg_iov[i].iov_len;

			/* netbuf empty, add new pbuf */
			if(chain_buf->p == NULL) {
				chain_buf->p = chain_buf->ptr = p;
				/* add pbuf to existing pbuf chain */
			} else {
				pbuf_cat(chain_buf->p, p);
			}
		}

		/* save size of total chain */
		if(err == ERR_OK) {
			size = netbuf_len(chain_buf);
		}

#endif /* LWIP_NETIF_TX_SINGLE_PBUF */

		if(err == ERR_OK) {
#if LWIP_IPV4 && LWIP_IPV6

			/* Dual-stack: Unmap IPv4 mapped IPv6 addresses */
			if(IP_IS_V6_VAL(chain_buf->addr) && ip6_addr_isipv4mappedipv6(ip_2_ip6(&chain_buf->addr))) {
				unmap_ipv4_mapped_ipv6(ip_2_ip4(&chain_buf->addr), ip_2_ip6(&chain_buf->addr));
				IP_SET_TYPE_VAL(chain_buf->addr, IPADDR_TYPE_V4);
			}

#endif /* LWIP_IPV4 && LWIP_IPV6 */

			/* send the data */
			err = netconn_send(sock->conn, chain_buf);
		}

		/* deallocated the buffer */
		netbuf_delete(chain_buf);

		sock_set_errno(sock, err_to_errno(err));
		return (err == ERR_OK ? size : -1);
	}
#else /* LWIP_UDP || LWIP_RAW */
	sock_set_errno(sock, err_to_errno(ERR_ARG));
	return -1;
#endif /* LWIP_UDP || LWIP_RAW */
}

int
lwip_sendto(int s, const void* data, size_t size, int flags,
            const struct sockaddr* to, socklen_t tolen)
{
	struct lwip_sock* sock;
	err_t err;
	u16_t short_size;
	u16_t remote_port;
	struct netbuf buf;

	sock = get_socket(s);

	if(!sock) {
		return -1;
	}

	if(NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) {
#if LWIP_TCP
		return lwip_send(s, data, size, flags);
#else /* LWIP_TCP */
		LWIP_UNUSED_ARG(flags);
		sock_set_errno(sock, err_to_errno(ERR_ARG));
		return -1;
#endif /* LWIP_TCP */
	}

	/* @todo: split into multiple sendto's? */
	LWIP_ASSERT("lwip_sendto: size must fit in u16_t", size <= 0xffff);
	short_size = (u16_t)size;
	LWIP_ERROR("lwip_sendto: invalid address", (((to == NULL) && (tolen == 0)) ||
	           (IS_SOCK_ADDR_LEN_VALID(tolen) &&
	            IS_SOCK_ADDR_TYPE_VALID(to) && IS_SOCK_ADDR_ALIGNED(to))),
	           sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);
	LWIP_UNUSED_ARG(tolen);

	/* initialize a buffer */
	buf.p = buf.ptr = NULL;
#if LWIP_CHECKSUM_ON_COPY
	buf.flags = 0;
#endif /* LWIP_CHECKSUM_ON_COPY */

	if(to) {
		SOCKADDR_TO_IPADDR_PORT(to, &buf.addr, remote_port);
	} else {
		remote_port = 0;
		ip_addr_set_any(NETCONNTYPE_ISIPV6(netconn_type(sock->conn)), &buf.addr);
	}

	netbuf_fromport(&buf) = remote_port;


	LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_sendto(%d, data=%p, short_size=%"U16_F", flags=0x%x to=",
	                            s, data, short_size, flags));
	ip_addr_debug_print(SOCKETS_DEBUG, &buf.addr);
	LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F"\n", remote_port));

	/* make the buffer point to the data that should be sent */
#if LWIP_NETIF_TX_SINGLE_PBUF

	/* Allocate a new netbuf and copy the data into it. */
	if(netbuf_alloc(&buf, short_size) == NULL) {
		err = ERR_MEM;
	} else {
#if LWIP_CHECKSUM_ON_COPY

		if(NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_RAW) {
			u16_t chksum = LWIP_CHKSUM_COPY(buf.p->payload, data, short_size);
			netbuf_set_chksum(&buf, chksum);
		} else
#endif /* LWIP_CHECKSUM_ON_COPY */
		{
			MEMCPY(buf.p->payload, data, short_size);
		}

		err = ERR_OK;
	}

#else /* LWIP_NETIF_TX_SINGLE_PBUF */
	err = netbuf_ref(&buf, data, short_size);
#endif /* LWIP_NETIF_TX_SINGLE_PBUF */

	if(err == ERR_OK) {
#if LWIP_IPV4 && LWIP_IPV6

		/* Dual-stack: Unmap IPv4 mapped IPv6 addresses */
		if(IP_IS_V6_VAL(buf.addr) && ip6_addr_isipv4mappedipv6(ip_2_ip6(&buf.addr))) {
			unmap_ipv4_mapped_ipv6(ip_2_ip4(&buf.addr), ip_2_ip6(&buf.addr));
			IP_SET_TYPE_VAL(buf.addr, IPADDR_TYPE_V4);
		}

#endif /* LWIP_IPV4 && LWIP_IPV6 */

		/* send the data */
		err = netconn_send(sock->conn, &buf);
	}

	/* deallocated the buffer */
	netbuf_free(&buf);

	sock_set_errno(sock, err_to_errno(err));
	return (err == ERR_OK ? short_size : -1);
}

int
lwip_socket(int domain, int type, int protocol)
{
	struct netconn* conn;
	int i;

	LWIP_UNUSED_ARG(domain); /* @todo: check this */

	/* create a netconn */
	switch(type) {
		case SOCK_RAW:
			conn = netconn_new_with_proto_and_callback(DOMAIN_TO_NETCONN_TYPE(domain, NETCONN_RAW),
			        (u8_t)protocol, event_callback);
			LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_socket(%s, SOCK_RAW, %d) = ",
			                            domain == PF_INET ? "PF_INET" : "UNKNOWN", protocol));
			break;

		case SOCK_DGRAM:
			conn = netconn_new_with_callback(DOMAIN_TO_NETCONN_TYPE(domain,
			                                 ((protocol == IPPROTO_UDPLITE) ? NETCONN_UDPLITE : NETCONN_UDP)),
			                                 event_callback);
			LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_socket(%s, SOCK_DGRAM, %d) = ",
			                            domain == PF_INET ? "PF_INET" : "UNKNOWN", protocol));
			break;

		case SOCK_STREAM:
			conn = netconn_new_with_callback(DOMAIN_TO_NETCONN_TYPE(domain, NETCONN_TCP), event_callback);
			LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_socket(%s, SOCK_STREAM, %d) = ",
			                            domain == PF_INET ? "PF_INET" : "UNKNOWN", protocol));
			break;

		default:
			LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_socket(%d, %d/UNKNOWN, %d) = -1\n",
			                            domain, type, protocol));
			set_errno(EINVAL);
			return -1;
	}

	if(!conn) {
		LWIP_DEBUGF(SOCKETS_DEBUG, ("-1 / ENOBUFS (could not create netconn)\n"));
		set_errno(ENOBUFS);
		return -1;
	}

	i = alloc_socket(conn, 0);

	if(i == -1) {
		netconn_delete(conn);
		set_errno(ENFILE);
		return -1;
	}

	conn->socket = i;
	LWIP_DEBUGF(SOCKETS_DEBUG, ("%d\n", i));
	set_errno(0);
	return i;
}

int
lwip_write(int s, const void* data, size_t size)
{
	return lwip_send(s, data, size, 0);
}

int
lwip_writev(int s, const struct iovec* iov, int iovcnt)
{
	struct msghdr msg;

	msg.msg_name = NULL;
	msg.msg_namelen = 0;
	/* Hack: we have to cast via number to cast from 'const' pointer to non-const.
	   Blame the opengroup standard for this inconsistency. */
	msg.msg_iov = LWIP_CONST_CAST(struct iovec*, iov);
	msg.msg_iovlen = iovcnt;
	msg.msg_control = NULL;
	msg.msg_controllen = 0;
	msg.msg_flags = 0;
	return lwip_sendmsg(s, &msg, 0);
}

/**
 * Go through the readset and writeset lists and see which socket of the sockets
 * set in the sets has events. On return, readset, writeset and exceptset have
 * the sockets enabled that had events.
 *
 * @param maxfdp1 the highest socket index in the sets
 * @param readset_in    set of sockets to check for read events
 * @param writeset_in   set of sockets to check for write events
 * @param exceptset_in  set of sockets to check for error events
 * @param readset_out   set of sockets that had read events
 * @param writeset_out  set of sockets that had write events
 * @param exceptset_out set os sockets that had error events
 * @return number of sockets that had events (read/write/exception) (>= 0)
 */
static int
lwip_selscan(int maxfdp1, fd_set* readset_in, fd_set* writeset_in, fd_set* exceptset_in,
             fd_set* readset_out, fd_set* writeset_out, fd_set* exceptset_out)
{
	int i, nready = 0;
	fd_set lreadset, lwriteset, lexceptset;
	struct lwip_sock* sock;
	SYS_ARCH_DECL_PROTECT(lev);

	FD_ZERO(&lreadset);
	FD_ZERO(&lwriteset);
	FD_ZERO(&lexceptset);

	/* Go through each socket in each list to count number of sockets which
	   currently match */
	for(i = LWIP_SOCKET_OFFSET; i < maxfdp1; i++) {
		/* if this FD is not in the set, continue */
		if(!(readset_in && FD_ISSET(i, readset_in)) &&
		        !(writeset_in && FD_ISSET(i, writeset_in)) &&
		        !(exceptset_in && FD_ISSET(i, exceptset_in))) {
			continue;
		}

		/* First get the socket's status (protected)... */
		SYS_ARCH_PROTECT(lev);
		sock = tryget_socket(i);

		if(sock != NULL) {
			void* lastdata = sock->lastdata;
			s16_t rcvevent = sock->rcvevent;
			u16_t sendevent = sock->sendevent;
			u16_t errevent = sock->errevent;
			SYS_ARCH_UNPROTECT(lev);

			/* ... then examine it: */
			/* See if netconn of this socket is ready for read */
			if(readset_in && FD_ISSET(i, readset_in) && ((lastdata != NULL) || (rcvevent > 0))) {
				FD_SET(i, &lreadset);
				LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_selscan: fd=%d ready for reading\n", i));
				nready++;
			}

			/* See if netconn of this socket is ready for write */
			if(writeset_in && FD_ISSET(i, writeset_in) && (sendevent != 0)) {
				FD_SET(i, &lwriteset);
				LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_selscan: fd=%d ready for writing\n", i));
				nready++;
			}

			/* See if netconn of this socket had an error */
			if(exceptset_in && FD_ISSET(i, exceptset_in) && (errevent != 0)) {
				FD_SET(i, &lexceptset);
				LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_selscan: fd=%d ready for exception\n", i));
				nready++;
			}
		} else {
			SYS_ARCH_UNPROTECT(lev);
			/* continue on to next FD in list */
		}
	}

	/* copy local sets to the ones provided as arguments */
	*readset_out = lreadset;
	*writeset_out = lwriteset;
	*exceptset_out = lexceptset;

	LWIP_ASSERT("nready >= 0", nready >= 0);
	return nready;
}

int
lwip_select(int maxfdp1, fd_set* readset, fd_set* writeset, fd_set* exceptset,
            struct timeval* timeout)
{
	u32_t waitres = 0;
	int nready;
	fd_set lreadset, lwriteset, lexceptset;
	u32_t msectimeout;
	struct lwip_select_cb select_cb;
	int i;
	int maxfdp2;
#if LWIP_NETCONN_SEM_PER_THREAD
	int waited = 0;
#endif
	SYS_ARCH_DECL_PROTECT(lev);

	LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select(%d, %p, %p, %p, tvsec=%"S32_F" tvusec=%"S32_F")\n",
	                            maxfdp1, (void*)readset, (void*) writeset, (void*) exceptset,
	                            timeout ? (s32_t)timeout->tv_sec : (s32_t) -1,
	                            timeout ? (s32_t)timeout->tv_usec : (s32_t) -1));

	/* Go through each socket in each list to count number of sockets which
	   currently match */
	nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset, &lwriteset, &lexceptset);

	/* If we don't have any current events, then suspend if we are supposed to */
	if(!nready) {
		if(timeout && timeout->tv_sec == 0 && timeout->tv_usec == 0) {
			LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: no timeout, returning 0\n"));
			/* This is OK as the local fdsets are empty and nready is zero,
			   or we would have returned earlier. */
			goto return_copy_fdsets;
		}

		/* None ready: add our semaphore to list:
		   We don't actually need any dynamic memory. Our entry on the
		   list is only valid while we are in this function, so it's ok
		   to use local variables. */

		select_cb.next = NULL;
		select_cb.prev = NULL;
		select_cb.readset = readset;
		select_cb.writeset = writeset;
		select_cb.exceptset = exceptset;
		select_cb.sem_signalled = 0;
#if LWIP_NETCONN_SEM_PER_THREAD
		select_cb.sem = LWIP_NETCONN_THREAD_SEM_GET();
#else /* LWIP_NETCONN_SEM_PER_THREAD */

		if(sys_sem_new(&select_cb.sem, 0) != ERR_OK) {
			/* failed to create semaphore */
			set_errno(ENOMEM);
			return -1;
		}

#endif /* LWIP_NETCONN_SEM_PER_THREAD */

		/* Protect the select_cb_list */
		SYS_ARCH_PROTECT(lev);

		/* Put this select_cb on top of list */
		select_cb.next = select_cb_list;

		if(select_cb_list != NULL) {
			select_cb_list->prev = &select_cb;
		}

		select_cb_list = &select_cb;
		/* Increasing this counter tells event_callback that the list has changed. */
		select_cb_ctr++;

		/* Now we can safely unprotect */
		SYS_ARCH_UNPROTECT(lev);

		/* Increase select_waiting for each socket we are interested in */
		maxfdp2 = maxfdp1;

		for(i = LWIP_SOCKET_OFFSET; i < maxfdp1; i++) {
			if((readset && FD_ISSET(i, readset)) ||
			        (writeset && FD_ISSET(i, writeset)) ||
			        (exceptset && FD_ISSET(i, exceptset))) {
				struct lwip_sock* sock;
				SYS_ARCH_PROTECT(lev);
				sock = tryget_socket(i);

				if(sock != NULL) {
					sock->select_waiting++;
					LWIP_ASSERT("sock->select_waiting > 0", sock->select_waiting > 0);
				} else {
					/* Not a valid socket */
					nready = -1;
					maxfdp2 = i;
					SYS_ARCH_UNPROTECT(lev);
					break;
				}

				SYS_ARCH_UNPROTECT(lev);
			}
		}

		if(nready >= 0) {
			/* Call lwip_selscan again: there could have been events between
			   the last scan (without us on the list) and putting us on the list! */
			nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset, &lwriteset, &lexceptset);

			if(!nready) {
				/* Still none ready, just wait to be woken */
				if(timeout == 0) {
					/* Wait forever */
					msectimeout = 0;
				} else {
					msectimeout = ((timeout->tv_sec * 1000) + ((timeout->tv_usec + 500) / 1000));

					if(msectimeout == 0) {
						/* Wait 1ms at least (0 means wait forever) */
						msectimeout = 1;
					}
				}

				waitres = sys_arch_sem_wait(SELECT_SEM_PTR(select_cb.sem), msectimeout);
#if LWIP_NETCONN_SEM_PER_THREAD
				waited = 1;
#endif
			}
		}

		/* Decrease select_waiting for each socket we are interested in */
		for(i = LWIP_SOCKET_OFFSET; i < maxfdp2; i++) {
			if((readset && FD_ISSET(i, readset)) ||
			        (writeset && FD_ISSET(i, writeset)) ||
			        (exceptset && FD_ISSET(i, exceptset))) {
				struct lwip_sock* sock;
				SYS_ARCH_PROTECT(lev);
				sock = tryget_socket(i);

				if(sock != NULL) {
					/* for now, handle select_waiting==0... */
					LWIP_ASSERT("sock->select_waiting > 0", sock->select_waiting > 0);

					if(sock->select_waiting > 0) {
						sock->select_waiting--;
					}
				} else {
					/* Not a valid socket */
					nready = -1;
				}

				SYS_ARCH_UNPROTECT(lev);
			}
		}

		/* Take us off the list */
		SYS_ARCH_PROTECT(lev);

		if(select_cb.next != NULL) {
			select_cb.next->prev = select_cb.prev;
		}

		if(select_cb_list == &select_cb) {
			LWIP_ASSERT("select_cb.prev == NULL", select_cb.prev == NULL);
			select_cb_list = select_cb.next;
		} else {
			LWIP_ASSERT("select_cb.prev != NULL", select_cb.prev != NULL);
			select_cb.prev->next = select_cb.next;
		}

		/* Increasing this counter tells event_callback that the list has changed. */
		select_cb_ctr++;
		SYS_ARCH_UNPROTECT(lev);

#if LWIP_NETCONN_SEM_PER_THREAD

		if(select_cb.sem_signalled && (!waited || (waitres == SYS_ARCH_TIMEOUT))) {
			/* don't leave the thread-local semaphore signalled */
			sys_arch_sem_wait(select_cb.sem, 1);
		}

#else /* LWIP_NETCONN_SEM_PER_THREAD */
		sys_sem_free(&select_cb.sem);
#endif /* LWIP_NETCONN_SEM_PER_THREAD */

		if(nready < 0) {
			/* This happens when a socket got closed while waiting */
			set_errno(EBADF);
			return -1;
		}

		if(waitres == SYS_ARCH_TIMEOUT) {
			/* Timeout */
			LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: timeout expired\n"));
			/* This is OK as the local fdsets are empty and nready is zero,
			   or we would have returned earlier. */
			goto return_copy_fdsets;
		}

		/* See what's set */
		nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset, &lwriteset, &lexceptset);
	}

	LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: nready=%d\n", nready));
return_copy_fdsets:
	set_errno(0);

	if(readset) {
		*readset = lreadset;
	}

	if(writeset) {
		*writeset = lwriteset;
	}

	if(exceptset) {
		*exceptset = lexceptset;
	}

	return nready;
}

/**
 * Callback registered in the netconn layer for each socket-netconn.
 * Processes recvevent (data available) and wakes up tasks waiting for select.
 */
static void
event_callback(struct netconn* conn, enum netconn_evt evt, u16_t len)
{
	int s;
	struct lwip_sock* sock;
	struct lwip_select_cb* scb;
	int last_select_cb_ctr;
	SYS_ARCH_DECL_PROTECT(lev);

	LWIP_UNUSED_ARG(len);

	/* Get socket */
	if(conn) {
		s = conn->socket;

		if(s < 0) {
			/* Data comes in right away after an accept, even though
			 * the server task might not have created a new socket yet.
			 * Just count down (or up) if that's the case and we
			 * will use the data later. Note that only receive events
			 * can happen before the new socket is set up. */
			SYS_ARCH_PROTECT(lev);

			if(conn->socket < 0) {
				if(evt == NETCONN_EVT_RCVPLUS) {
					conn->socket--;
				}

				SYS_ARCH_UNPROTECT(lev);
				return;
			}

			s = conn->socket;
			SYS_ARCH_UNPROTECT(lev);
		}

		sock = get_socket(s);

		if(!sock) {
			return;
		}
	} else {
		return;
	}

	SYS_ARCH_PROTECT(lev);

	/* Set event as required */
	switch(evt) {
		case NETCONN_EVT_RCVPLUS:
			sock->rcvevent++;
			break;

		case NETCONN_EVT_RCVMINUS:
			sock->rcvevent--;
			break;

		case NETCONN_EVT_SENDPLUS:
			sock->sendevent = 1;
			break;

		case NETCONN_EVT_SENDMINUS:
			sock->sendevent = 0;
			break;

		case NETCONN_EVT_ERROR:
			sock->errevent = 1;
			break;

		default:
			LWIP_ASSERT("unknown event", 0);
			break;
	}

	if(sock->select_waiting == 0) {
		/* noone is waiting for this socket, no need to check select_cb_list */
		SYS_ARCH_UNPROTECT(lev);
		return;
	}

	/* Now decide if anyone is waiting for this socket */
	/* NOTE: This code goes through the select_cb_list list multiple times
	   ONLY IF a select was actually waiting. We go through the list the number
	   of waiting select calls + 1. This list is expected to be small. */

	/* At this point, SYS_ARCH is still protected! */
again:

	for(scb = select_cb_list; scb != NULL; scb = scb->next) {
		/* remember the state of select_cb_list to detect changes */
		last_select_cb_ctr = select_cb_ctr;

		if(scb->sem_signalled == 0) {
			/* semaphore not signalled yet */
			int do_signal = 0;

			/* Test this select call for our socket */
			if(sock->rcvevent > 0) {
				if(scb->readset && FD_ISSET(s, scb->readset)) {
					do_signal = 1;
				}
			}

			if(sock->sendevent != 0) {
				if(!do_signal && scb->writeset && FD_ISSET(s, scb->writeset)) {
					do_signal = 1;
				}
			}

			if(sock->errevent != 0) {
				if(!do_signal && scb->exceptset && FD_ISSET(s, scb->exceptset)) {
					do_signal = 1;
				}
			}

			if(do_signal) {
				scb->sem_signalled = 1;
				/* Don't call SYS_ARCH_UNPROTECT() before signaling the semaphore, as this might
				   lead to the select thread taking itself off the list, invalidating the semaphore. */
				sys_sem_signal(SELECT_SEM_PTR(scb->sem));
			}
		}

		/* unlock interrupts with each step */
		SYS_ARCH_UNPROTECT(lev);
		/* this makes sure interrupt protection time is short */
		SYS_ARCH_PROTECT(lev);

		if(last_select_cb_ctr != select_cb_ctr) {
			/* someone has changed select_cb_list, restart at the beginning */
			goto again;
		}
	}

	SYS_ARCH_UNPROTECT(lev);
}

/**
 * Close one end of a full-duplex connection.
 */
int
lwip_shutdown(int s, int how)
{
	struct lwip_sock* sock;
	err_t err;
	u8_t shut_rx = 0, shut_tx = 0;

	LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_shutdown(%d, how=%d)\n", s, how));

	sock = get_socket(s);

	if(!sock) {
		return -1;
	}

	if(sock->conn != NULL) {
		if(NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_TCP) {
			sock_set_errno(sock, EOPNOTSUPP);
			return -1;
		}
	} else {
		sock_set_errno(sock, ENOTCONN);
		return -1;
	}

	if(how == SHUT_RD) {
		shut_rx = 1;
	} else if(how == SHUT_WR) {
		shut_tx = 1;
	} else if(how == SHUT_RDWR) {
		shut_rx = 1;
		shut_tx = 1;
	} else {
		sock_set_errno(sock, EINVAL);
		return -1;
	}

	err = netconn_shutdown(sock->conn, shut_rx, shut_tx);

	sock_set_errno(sock, err_to_errno(err));
	return (err == ERR_OK ? 0 : -1);
}

static int
lwip_getaddrname(int s, struct sockaddr* name, socklen_t* namelen, u8_t local)
{
	struct lwip_sock* sock;
	union sockaddr_aligned saddr;
	ip_addr_t naddr;
	u16_t port;
	err_t err;

	sock = get_socket(s);

	if(!sock) {
		return -1;
	}

	/* get the IP address and port */
	err = netconn_getaddr(sock->conn, &naddr, &port, local);

	if(err != ERR_OK) {
		sock_set_errno(sock, err_to_errno(err));
		return -1;
	}

#if LWIP_IPV4 && LWIP_IPV6

	/* Dual-stack: Map IPv4 addresses to IPv4 mapped IPv6 */
	if(NETCONNTYPE_ISIPV6(netconn_type(sock->conn)) &&
	        IP_IS_V4_VAL(naddr)) {
		ip4_2_ipv4_mapped_ipv6(ip_2_ip6(&naddr), ip_2_ip4(&naddr));
		IP_SET_TYPE_VAL(naddr, IPADDR_TYPE_V6);
	}

#endif /* LWIP_IPV4 && LWIP_IPV6 */

	IPADDR_PORT_TO_SOCKADDR(&saddr, &naddr, port);

	LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getaddrname(%d, addr=", s));
	ip_addr_debug_print_val(SOCKETS_DEBUG, naddr);
	LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F")\n", port));

	if(*namelen > saddr.sa.sa_len) {
		*namelen = saddr.sa.sa_len;
	}

	MEMCPY(name, &saddr, *namelen);

	sock_set_errno(sock, 0);
	return 0;
}

int
lwip_getpeername(int s, struct sockaddr* name, socklen_t* namelen)
{
	return lwip_getaddrname(s, name, namelen, 0);
}

int
lwip_getsockname(int s, struct sockaddr* name, socklen_t* namelen)
{
	return lwip_getaddrname(s, name, namelen, 1);
}

int
lwip_getsockopt(int s, int level, int optname, void* optval, socklen_t* optlen)
{
	u8_t err;
	struct lwip_sock* sock = get_socket(s);
#if !LWIP_TCPIP_CORE_LOCKING
	LWIP_SETGETSOCKOPT_DATA_VAR_DECLARE(data);
#endif /* !LWIP_TCPIP_CORE_LOCKING */

	if(!sock) {
		return -1;
	}

	if((NULL == optval) || (NULL == optlen)) {
		sock_set_errno(sock, EFAULT);
		return -1;
	}

#if LWIP_TCPIP_CORE_LOCKING
	/* core-locking can just call the -impl function */
	LOCK_TCPIP_CORE();
	err = lwip_getsockopt_impl(s, level, optname, optval, optlen);
	UNLOCK_TCPIP_CORE();

#else /* LWIP_TCPIP_CORE_LOCKING */

#if LWIP_MPU_COMPATIBLE

	/* MPU_COMPATIBLE copies the optval data, so check for max size here */
	if(*optlen > LWIP_SETGETSOCKOPT_MAXOPTLEN) {
		sock_set_errno(sock, ENOBUFS);
		return -1;
	}

#endif /* LWIP_MPU_COMPATIBLE */

	LWIP_SETGETSOCKOPT_DATA_VAR_ALLOC(data, sock);
	LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).s = s;
	LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).level = level;
	LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optname = optname;
	LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optlen = *optlen;
#if !LWIP_MPU_COMPATIBLE
	LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optval.p = optval;
#endif /* !LWIP_MPU_COMPATIBLE */
	LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).err = 0;
#if LWIP_NETCONN_SEM_PER_THREAD
	LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).completed_sem = LWIP_NETCONN_THREAD_SEM_GET();
#else
	LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).completed_sem = &sock->conn->op_completed;
#endif
	err = tcpip_callback(lwip_getsockopt_callback, &LWIP_SETGETSOCKOPT_DATA_VAR_REF(data));

	if(err != ERR_OK) {
		LWIP_SETGETSOCKOPT_DATA_VAR_FREE(data);
		sock_set_errno(sock, err_to_errno(err));
		return -1;
	}

	sys_arch_sem_wait((sys_sem_t*)(LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).completed_sem), 0);

	/* write back optlen and optval */
	*optlen = LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optlen;
#if LWIP_MPU_COMPATIBLE
	MEMCPY(optval, LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optval,
	       LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optlen);
#endif /* LWIP_MPU_COMPATIBLE */

	/* maybe lwip_getsockopt_internal has changed err */
	err = LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).err;
	LWIP_SETGETSOCKOPT_DATA_VAR_FREE(data);
#endif /* LWIP_TCPIP_CORE_LOCKING */

	sock_set_errno(sock, err);
	return err ? -1 : 0;
}

#if !LWIP_TCPIP_CORE_LOCKING
/** lwip_getsockopt_callback: only used without CORE_LOCKING
 * to get into the tcpip_thread
 */
static void
lwip_getsockopt_callback(void* arg)
{
	struct lwip_setgetsockopt_data* data;
	LWIP_ASSERT("arg != NULL", arg != NULL);
	data = (struct lwip_setgetsockopt_data*)arg;

	data->err = lwip_getsockopt_impl(data->s, data->level, data->optname,
#if LWIP_MPU_COMPATIBLE
	                                 data->optval,
#else /* LWIP_MPU_COMPATIBLE */
	                                 data->optval.p,
#endif /* LWIP_MPU_COMPATIBLE */
	                                 &data->optlen);

	sys_sem_signal((sys_sem_t*)(data->completed_sem));
}
#endif  /* LWIP_TCPIP_CORE_LOCKING */

/** lwip_getsockopt_impl: the actual implementation of getsockopt:
 * same argument as lwip_getsockopt, either called directly or through callback
 */
static u8_t
lwip_getsockopt_impl(int s, int level, int optname, void* optval, socklen_t* optlen)
{
	u8_t err = 0;
	struct lwip_sock* sock = tryget_socket(s);

	if(!sock) {
		return EBADF;
	}

	switch(level) {

		/* Level: SOL_SOCKET */
		case SOL_SOCKET:
			switch(optname) {

#if LWIP_TCP

				case SO_ACCEPTCONN:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, *optlen, int);

					if(NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_TCP) {
						return ENOPROTOOPT;
					}

					if((sock->conn->pcb.tcp != NULL) && (sock->conn->pcb.tcp->state == LISTEN)) {
						*(int*)optval = 1;
					} else {
						*(int*)optval = 0;
					}

					break;
#endif /* LWIP_TCP */

				/* The option flags */
				case SO_BROADCAST:
				case SO_KEEPALIVE:
#if SO_REUSE
				case SO_REUSEADDR:
#endif /* SO_REUSE */
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, *optlen, int);
					*(int*)optval = ip_get_option(sock->conn->pcb.ip, optname);
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, SOL_SOCKET, optname=0x%x, ..) = %s\n",
					                            s, optname, (*(int*)optval ? "on" : "off")));
					break;

				case SO_TYPE:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, *optlen, int);

					switch(NETCONNTYPE_GROUP(netconn_type(sock->conn))) {
						case NETCONN_RAW:
							*(int*)optval = SOCK_RAW;
							break;

						case NETCONN_TCP:
							*(int*)optval = SOCK_STREAM;
							break;

						case NETCONN_UDP:
							*(int*)optval = SOCK_DGRAM;
							break;

						default: /* unrecognized socket type */
							*(int*)optval = netconn_type(sock->conn);
							LWIP_DEBUGF(SOCKETS_DEBUG,
							            ("lwip_getsockopt(%d, SOL_SOCKET, SO_TYPE): unrecognized socket type %d\n",
							             s, *(int*)optval));
					}  /* switch (netconn_type(sock->conn)) */

					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, SOL_SOCKET, SO_TYPE) = %d\n",
					                            s, *(int*)optval));
					break;

				case SO_ERROR:
					LWIP_SOCKOPT_CHECK_OPTLEN(*optlen, int);

					/* only overwrite ERR_OK or temporary errors */
					if(((sock->err == 0) || (sock->err == EINPROGRESS)) && (sock->conn != NULL)) {
						sock_set_errno(sock, err_to_errno(sock->conn->last_err));
					}

					*(int*)optval = (sock->err == 0xFF ? (int) -1 : (int)sock->err);
					sock->err = 0;
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, SOL_SOCKET, SO_ERROR) = %d\n",
					                            s, *(int*)optval));
					break;

#if LWIP_SO_SNDTIMEO

				case SO_SNDTIMEO:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, *optlen, LWIP_SO_SNDRCVTIMEO_OPTTYPE);
					LWIP_SO_SNDRCVTIMEO_SET(optval, netconn_get_sendtimeout(sock->conn));
					break;
#endif /* LWIP_SO_SNDTIMEO */
#if LWIP_SO_RCVTIMEO

				case SO_RCVTIMEO:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, *optlen, LWIP_SO_SNDRCVTIMEO_OPTTYPE);
					LWIP_SO_SNDRCVTIMEO_SET(optval, netconn_get_recvtimeout(sock->conn));
					break;
#endif /* LWIP_SO_RCVTIMEO */
#if LWIP_SO_RCVBUF

				case SO_RCVBUF:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, *optlen, int);
					*(int*)optval = netconn_get_recvbufsize(sock->conn);
					break;
#endif /* LWIP_SO_RCVBUF */
#if LWIP_SO_LINGER

				case SO_LINGER: {
					s16_t conn_linger;
					struct linger* linger = (struct linger*)optval;
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, *optlen, struct linger);
					conn_linger = sock->conn->linger;

					if(conn_linger >= 0) {
						linger->l_onoff = 1;
						linger->l_linger = (int)conn_linger;
					} else {
						linger->l_onoff = 0;
						linger->l_linger = 0;
					}
				}
				break;
#endif /* LWIP_SO_LINGER */
#if LWIP_UDP

				case SO_NO_CHECK:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, *optlen, int, NETCONN_UDP);
#if LWIP_UDPLITE

					if((udp_flags(sock->conn->pcb.udp) & UDP_FLAGS_UDPLITE) != 0) {
						/* this flag is only available for UDP, not for UDP lite */
						return EAFNOSUPPORT;
					}

#endif /* LWIP_UDPLITE */
					*(int*)optval = (udp_flags(sock->conn->pcb.udp) & UDP_FLAGS_NOCHKSUM) ? 1 : 0;
					break;
#endif /* LWIP_UDP*/

				default:
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, SOL_SOCKET, UNIMPL: optname=0x%x, ..)\n",
					                            s, optname));
					err = ENOPROTOOPT;
					break;
			}  /* switch (optname) */

			break;

		/* Level: IPPROTO_IP */
		case IPPROTO_IP:
			switch(optname) {
				case IP_TTL:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, *optlen, int);
					*(int*)optval = sock->conn->pcb.ip->ttl;
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_TTL) = %d\n",
					                            s, *(int*)optval));
					break;

				case IP_TOS:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, *optlen, int);
					*(int*)optval = sock->conn->pcb.ip->tos;
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_TOS) = %d\n",
					                            s, *(int*)optval));
					break;
#if LWIP_MULTICAST_TX_OPTIONS

				case IP_MULTICAST_TTL:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, *optlen, u8_t);

					if(NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_UDP) {
						return ENOPROTOOPT;
					}

					*(u8_t*)optval = udp_get_multicast_ttl(sock->conn->pcb.udp);
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_TTL) = %d\n",
					                            s, *(int*)optval));
					break;

				case IP_MULTICAST_IF:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, *optlen, struct in_addr);

					if(NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_UDP) {
						return ENOPROTOOPT;
					}

					inet_addr_from_ip4addr((struct in_addr*)optval, udp_get_multicast_netif_addr(sock->conn->pcb.udp));
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_IF) = 0x%"X32_F"\n",
					                            s, *(u32_t*)optval));
					break;

				case IP_MULTICAST_LOOP:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, *optlen, u8_t);

					if((sock->conn->pcb.udp->flags & UDP_FLAGS_MULTICAST_LOOP) != 0) {
						*(u8_t*)optval = 1;
					} else {
						*(u8_t*)optval = 0;
					}

					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_LOOP) = %d\n",
					                            s, *(int*)optval));
					break;
#endif /* LWIP_MULTICAST_TX_OPTIONS */

				default:
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, UNIMPL: optname=0x%x, ..)\n",
					                            s, optname));
					err = ENOPROTOOPT;
					break;
			}  /* switch (optname) */

			break;

#if LWIP_TCP

		/* Level: IPPROTO_TCP */
		case IPPROTO_TCP:
			/* Special case: all IPPROTO_TCP option take an int */
			LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, *optlen, int, NETCONN_TCP);

			if(sock->conn->pcb.tcp->state == LISTEN) {
				return EINVAL;
			}

			switch(optname) {
				case TCP_NODELAY:
					*(int*)optval = tcp_nagle_disabled(sock->conn->pcb.tcp);
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_TCP, TCP_NODELAY) = %s\n",
					                            s, (*(int*)optval) ? "on" : "off"));
					break;

				case TCP_KEEPALIVE:
					*(int*)optval = (int)sock->conn->pcb.tcp->keep_idle;
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_TCP, TCP_KEEPALIVE) = %d\n",
					                            s, *(int*)optval));
					break;

#if LWIP_TCP_KEEPALIVE

				case TCP_KEEPIDLE:
					*(int*)optval = (int)(sock->conn->pcb.tcp->keep_idle / 1000);
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_TCP, TCP_KEEPIDLE) = %d\n",
					                            s, *(int*)optval));
					break;

				case TCP_KEEPINTVL:
					*(int*)optval = (int)(sock->conn->pcb.tcp->keep_intvl / 1000);
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_TCP, TCP_KEEPINTVL) = %d\n",
					                            s, *(int*)optval));
					break;

				case TCP_KEEPCNT:
					*(int*)optval = (int)sock->conn->pcb.tcp->keep_cnt;
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_TCP, TCP_KEEPCNT) = %d\n",
					                            s, *(int*)optval));
					break;
#endif /* LWIP_TCP_KEEPALIVE */

				default:
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_TCP, UNIMPL: optname=0x%x, ..)\n",
					                            s, optname));
					err = ENOPROTOOPT;
					break;
			}  /* switch (optname) */

			break;
#endif /* LWIP_TCP */

#if LWIP_IPV6

		/* Level: IPPROTO_IPV6 */
		case IPPROTO_IPV6:
			switch(optname) {
				case IPV6_V6ONLY:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, *optlen, int);
					*(int*)optval = (netconn_get_ipv6only(sock->conn) ? 1 : 0);
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IPV6, IPV6_V6ONLY) = %d\n",
					                            s, *(int*)optval));
					break;

				default:
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IPV6, UNIMPL: optname=0x%x, ..)\n",
					                            s, optname));
					err = ENOPROTOOPT;
					break;
			}  /* switch (optname) */

			break;
#endif /* LWIP_IPV6 */

#if LWIP_UDP && LWIP_UDPLITE

		/* Level: IPPROTO_UDPLITE */
		case IPPROTO_UDPLITE:
			/* Special case: all IPPROTO_UDPLITE option take an int */
			LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, *optlen, int);

			/* If this is no UDP lite socket, ignore any options. */
			if(!NETCONNTYPE_ISUDPLITE(netconn_type(sock->conn))) {
				return ENOPROTOOPT;
			}

			switch(optname) {
				case UDPLITE_SEND_CSCOV:
					*(int*)optval = sock->conn->pcb.udp->chksum_len_tx;
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_UDPLITE, UDPLITE_SEND_CSCOV) = %d\n",
					                            s, (*(int*)optval)));
					break;

				case UDPLITE_RECV_CSCOV:
					*(int*)optval = sock->conn->pcb.udp->chksum_len_rx;
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_UDPLITE, UDPLITE_RECV_CSCOV) = %d\n",
					                            s, (*(int*)optval)));
					break;

				default:
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_UDPLITE, UNIMPL: optname=0x%x, ..)\n",
					                            s, optname));
					err = ENOPROTOOPT;
					break;
			}  /* switch (optname) */

			break;
#endif /* LWIP_UDP */

		/* Level: IPPROTO_RAW */
		case IPPROTO_RAW:
			switch(optname) {
#if LWIP_IPV6 && LWIP_RAW

				case IPV6_CHECKSUM:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, *optlen, int, NETCONN_RAW);

					if(sock->conn->pcb.raw->chksum_reqd == 0) {
						*(int*)optval = -1;
					} else {
						*(int*)optval = sock->conn->pcb.raw->chksum_offset;
					}

					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_RAW, IPV6_CHECKSUM) = %d\n",
					                            s, (*(int*)optval)));
					break;
#endif /* LWIP_IPV6 && LWIP_RAW */

				default:
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_RAW, UNIMPL: optname=0x%x, ..)\n",
					                            s, optname));
					err = ENOPROTOOPT;
					break;
			}  /* switch (optname) */

			break;

		default:
			LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, level=0x%x, UNIMPL: optname=0x%x, ..)\n",
			                            s, level, optname));
			err = ENOPROTOOPT;
			break;
	} /* switch (level) */

	return err;
}

int
lwip_setsockopt(int s, int level, int optname, const void* optval, socklen_t optlen)
{
	u8_t err = 0;
	struct lwip_sock* sock = get_socket(s);
#if !LWIP_TCPIP_CORE_LOCKING
	LWIP_SETGETSOCKOPT_DATA_VAR_DECLARE(data);
#endif /* !LWIP_TCPIP_CORE_LOCKING */

	if(!sock) {
		return -1;
	}

	if(NULL == optval) {
		sock_set_errno(sock, EFAULT);
		return -1;
	}

#if LWIP_TCPIP_CORE_LOCKING
	/* core-locking can just call the -impl function */
	LOCK_TCPIP_CORE();
	err = lwip_setsockopt_impl(s, level, optname, optval, optlen);
	UNLOCK_TCPIP_CORE();

#else /* LWIP_TCPIP_CORE_LOCKING */

#if LWIP_MPU_COMPATIBLE

	/* MPU_COMPATIBLE copies the optval data, so check for max size here */
	if(optlen > LWIP_SETGETSOCKOPT_MAXOPTLEN) {
		sock_set_errno(sock, ENOBUFS);
		return -1;
	}

#endif /* LWIP_MPU_COMPATIBLE */

	LWIP_SETGETSOCKOPT_DATA_VAR_ALLOC(data, sock);
	LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).s = s;
	LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).level = level;
	LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optname = optname;
	LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optlen = optlen;
#if LWIP_MPU_COMPATIBLE
	MEMCPY(LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optval, optval, optlen);
#else /* LWIP_MPU_COMPATIBLE */
	LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optval.pc = (const void*)optval;
#endif /* LWIP_MPU_COMPATIBLE */
	LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).err = 0;
#if LWIP_NETCONN_SEM_PER_THREAD
	LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).completed_sem = LWIP_NETCONN_THREAD_SEM_GET();
#else
	LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).completed_sem = &sock->conn->op_completed;
#endif
	err = tcpip_callback(lwip_setsockopt_callback, &LWIP_SETGETSOCKOPT_DATA_VAR_REF(data));

	if(err != ERR_OK) {
		LWIP_SETGETSOCKOPT_DATA_VAR_FREE(data);
		sock_set_errno(sock, err_to_errno(err));
		return -1;
	}

	sys_arch_sem_wait((sys_sem_t*)(LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).completed_sem), 0);

	/* maybe lwip_getsockopt_internal has changed err */
	err = LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).err;
	LWIP_SETGETSOCKOPT_DATA_VAR_FREE(data);
#endif  /* LWIP_TCPIP_CORE_LOCKING */

	sock_set_errno(sock, err);
	return err ? -1 : 0;
}

#if !LWIP_TCPIP_CORE_LOCKING
/** lwip_setsockopt_callback: only used without CORE_LOCKING
 * to get into the tcpip_thread
 */
static void
lwip_setsockopt_callback(void* arg)
{
	struct lwip_setgetsockopt_data* data;
	LWIP_ASSERT("arg != NULL", arg != NULL);
	data = (struct lwip_setgetsockopt_data*)arg;

	data->err = lwip_setsockopt_impl(data->s, data->level, data->optname,
#if LWIP_MPU_COMPATIBLE
	                                 data->optval,
#else /* LWIP_MPU_COMPATIBLE */
	                                 data->optval.pc,
#endif /* LWIP_MPU_COMPATIBLE */
	                                 data->optlen);

	sys_sem_signal((sys_sem_t*)(data->completed_sem));
}
#endif  /* LWIP_TCPIP_CORE_LOCKING */

/** lwip_setsockopt_impl: the actual implementation of setsockopt:
 * same argument as lwip_setsockopt, either called directly or through callback
 */
static u8_t
lwip_setsockopt_impl(int s, int level, int optname, const void* optval, socklen_t optlen)
{
	u8_t err = 0;
	struct lwip_sock* sock = tryget_socket(s);

	if(!sock) {
		return EBADF;
	}

	switch(level) {

		/* Level: SOL_SOCKET */
		case SOL_SOCKET:
			switch(optname) {

				/* SO_ACCEPTCONN is get-only */

				/* The option flags */
				case SO_BROADCAST:
				case SO_KEEPALIVE:
#if SO_REUSE
				case SO_REUSEADDR:
#endif /* SO_REUSE */
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, optlen, int);

					if(*(const int*)optval) {
						ip_set_option(sock->conn->pcb.ip, optname);
					} else {
						ip_reset_option(sock->conn->pcb.ip, optname);
					}

					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, SOL_SOCKET, optname=0x%x, ..) -> %s\n",
					                            s, optname, (*(const int*)optval ? "on" : "off")));
					break;

					/* SO_TYPE is get-only */
					/* SO_ERROR is get-only */

#if LWIP_SO_SNDTIMEO

				case SO_SNDTIMEO:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, optlen, LWIP_SO_SNDRCVTIMEO_OPTTYPE);
					netconn_set_sendtimeout(sock->conn, LWIP_SO_SNDRCVTIMEO_GET_MS(optval));
					break;
#endif /* LWIP_SO_SNDTIMEO */
#if LWIP_SO_RCVTIMEO

				case SO_RCVTIMEO:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, optlen, LWIP_SO_SNDRCVTIMEO_OPTTYPE);
					netconn_set_recvtimeout(sock->conn, (int)LWIP_SO_SNDRCVTIMEO_GET_MS(optval));
					break;
#endif /* LWIP_SO_RCVTIMEO */
#if LWIP_SO_RCVBUF

				case SO_RCVBUF:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, optlen, int);
					netconn_set_recvbufsize(sock->conn, *(const int*)optval);
					break;
#endif /* LWIP_SO_RCVBUF */
#if LWIP_SO_LINGER

				case SO_LINGER: {
					const struct linger* linger = (const struct linger*)optval;
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, optlen, struct linger);

					if(linger->l_onoff) {
						int lingersec = linger->l_linger;

						if(lingersec < 0) {
							return EINVAL;
						}

						if(lingersec > 0xFFFF) {
							lingersec = 0xFFFF;
						}

						sock->conn->linger = (s16_t)lingersec;
					} else {
						sock->conn->linger = -1;
					}
				}
				break;
#endif /* LWIP_SO_LINGER */
#if LWIP_UDP

				case SO_NO_CHECK:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, int, NETCONN_UDP);
#if LWIP_UDPLITE

					if((udp_flags(sock->conn->pcb.udp) & UDP_FLAGS_UDPLITE) != 0) {
						/* this flag is only available for UDP, not for UDP lite */
						return EAFNOSUPPORT;
					}

#endif /* LWIP_UDPLITE */

					if(*(const int*)optval) {
						udp_setflags(sock->conn->pcb.udp, udp_flags(sock->conn->pcb.udp) | UDP_FLAGS_NOCHKSUM);
					} else {
						udp_setflags(sock->conn->pcb.udp, udp_flags(sock->conn->pcb.udp) & ~UDP_FLAGS_NOCHKSUM);
					}

					break;
#endif /* LWIP_UDP */

				default:
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, SOL_SOCKET, UNIMPL: optname=0x%x, ..)\n",
					                            s, optname));
					err = ENOPROTOOPT;
					break;
			}  /* switch (optname) */

			break;

		/* Level: IPPROTO_IP */
		case IPPROTO_IP:
			switch(optname) {
				case IP_TTL:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, optlen, int);
					sock->conn->pcb.ip->ttl = (u8_t)(*(const int*)optval);
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_IP, IP_TTL, ..) -> %d\n",
					                            s, sock->conn->pcb.ip->ttl));
					break;

				case IP_TOS:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, optlen, int);
					sock->conn->pcb.ip->tos = (u8_t)(*(const int*)optval);
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_IP, IP_TOS, ..)-> %d\n",
					                            s, sock->conn->pcb.ip->tos));
					break;
#if LWIP_MULTICAST_TX_OPTIONS

				case IP_MULTICAST_TTL:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, u8_t, NETCONN_UDP);
					udp_set_multicast_ttl(sock->conn->pcb.udp, (u8_t)(*(const u8_t*)optval));
					break;

				case IP_MULTICAST_IF: {
					ip4_addr_t if_addr;
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, struct in_addr, NETCONN_UDP);
					inet_addr_to_ip4addr(&if_addr, (const struct in_addr*)optval);
					udp_set_multicast_netif_addr(sock->conn->pcb.udp, &if_addr);
				}
				break;

				case IP_MULTICAST_LOOP:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, u8_t, NETCONN_UDP);

					if(*(const u8_t*)optval) {
						udp_setflags(sock->conn->pcb.udp, udp_flags(sock->conn->pcb.udp) | UDP_FLAGS_MULTICAST_LOOP);
					} else {
						udp_setflags(sock->conn->pcb.udp, udp_flags(sock->conn->pcb.udp) & ~UDP_FLAGS_MULTICAST_LOOP);
					}

					break;
#endif /* LWIP_MULTICAST_TX_OPTIONS */
#if LWIP_IGMP

				case IP_ADD_MEMBERSHIP:
				case IP_DROP_MEMBERSHIP: {
					/* If this is a TCP or a RAW socket, ignore these options. */
					/* @todo: assign membership to this socket so that it is dropped when closing the socket */
					err_t igmp_err;
					const struct ip_mreq* imr = (const struct ip_mreq*)optval;
					ip4_addr_t if_addr;
					ip4_addr_t multi_addr;
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, struct ip_mreq, NETCONN_UDP);
					inet_addr_to_ip4addr(&if_addr, &imr->imr_interface);
					inet_addr_to_ip4addr(&multi_addr, &imr->imr_multiaddr);

					if(optname == IP_ADD_MEMBERSHIP) {
						if(!lwip_socket_register_membership(s, &if_addr, &multi_addr)) {
							/* cannot track membership (out of memory) */
							err = ENOMEM;
							igmp_err = ERR_OK;
						} else {
							igmp_err = igmp_joingroup(&if_addr, &multi_addr);
						}
					} else {
						igmp_err = igmp_leavegroup(&if_addr, &multi_addr);
						lwip_socket_unregister_membership(s, &if_addr, &multi_addr);
					}

					if(igmp_err != ERR_OK) {
						err = EADDRNOTAVAIL;
					}
				}
				break;
#endif /* LWIP_IGMP */

				default:
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_IP, UNIMPL: optname=0x%x, ..)\n",
					                            s, optname));
					err = ENOPROTOOPT;
					break;
			}  /* switch (optname) */

			break;

#if LWIP_TCP

		/* Level: IPPROTO_TCP */
		case IPPROTO_TCP:
			/* Special case: all IPPROTO_TCP option take an int */
			LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, int, NETCONN_TCP);

			if(sock->conn->pcb.tcp->state == LISTEN) {
				return EINVAL;
			}

			switch(optname) {
				case TCP_NODELAY:
					if(*(const int*)optval) {
						tcp_nagle_disable(sock->conn->pcb.tcp);
					} else {
						tcp_nagle_enable(sock->conn->pcb.tcp);
					}

					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_NODELAY) -> %s\n",
					                            s, (*(const int*)optval) ? "on" : "off"));
					break;

				case TCP_KEEPALIVE:
					sock->conn->pcb.tcp->keep_idle = (u32_t)(*(const int*)optval);
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_KEEPALIVE) -> %"U32_F"\n",
					                            s, sock->conn->pcb.tcp->keep_idle));
					break;

#if LWIP_TCP_KEEPALIVE

				case TCP_KEEPIDLE:
					sock->conn->pcb.tcp->keep_idle = 1000 * (u32_t)(*(const int*)optval);
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_KEEPIDLE) -> %"U32_F"\n",
					                            s, sock->conn->pcb.tcp->keep_idle));
					break;

				case TCP_KEEPINTVL:
					sock->conn->pcb.tcp->keep_intvl = 1000 * (u32_t)(*(const int*)optval);
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_KEEPINTVL) -> %"U32_F"\n",
					                            s, sock->conn->pcb.tcp->keep_intvl));
					break;

				case TCP_KEEPCNT:
					sock->conn->pcb.tcp->keep_cnt = (u32_t)(*(const int*)optval);
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_KEEPCNT) -> %"U32_F"\n",
					                            s, sock->conn->pcb.tcp->keep_cnt));
					break;
#endif /* LWIP_TCP_KEEPALIVE */

				default:
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, UNIMPL: optname=0x%x, ..)\n",
					                            s, optname));
					err = ENOPROTOOPT;
					break;
			}  /* switch (optname) */

			break;
#endif /* LWIP_TCP*/

#if LWIP_IPV6

		/* Level: IPPROTO_IPV6 */
		case IPPROTO_IPV6:
			switch(optname) {
				case IPV6_V6ONLY:
					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, int, NETCONN_TCP);

					if(*(const int*)optval) {
						netconn_set_ipv6only(sock->conn, 1);
					} else {
						netconn_set_ipv6only(sock->conn, 0);
					}

					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_IPV6, IPV6_V6ONLY, ..) -> %d\n",
					                            s, (netconn_get_ipv6only(sock->conn) ? 1 : 0)));
					break;

				default:
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_IPV6, UNIMPL: optname=0x%x, ..)\n",
					                            s, optname));
					err = ENOPROTOOPT;
					break;
			}  /* switch (optname) */

			break;
#endif /* LWIP_IPV6 */

#if LWIP_UDP && LWIP_UDPLITE

		/* Level: IPPROTO_UDPLITE */
		case IPPROTO_UDPLITE:
			/* Special case: all IPPROTO_UDPLITE option take an int */
			LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, optlen, int);

			/* If this is no UDP lite socket, ignore any options. */
			if(!NETCONNTYPE_ISUDPLITE(netconn_type(sock->conn))) {
				return ENOPROTOOPT;
			}

			switch(optname) {
				case UDPLITE_SEND_CSCOV:
					if((*(const int*)optval != 0) && ((*(const int*)optval < 8) || (*(const int*)optval > 0xffff))) {
						/* don't allow illegal values! */
						sock->conn->pcb.udp->chksum_len_tx = 8;
					} else {
						sock->conn->pcb.udp->chksum_len_tx = (u16_t) * (const int*)optval;
					}

					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_UDPLITE, UDPLITE_SEND_CSCOV) -> %d\n",
					                            s, (*(const int*)optval)));
					break;

				case UDPLITE_RECV_CSCOV:
					if((*(const int*)optval != 0) && ((*(const int*)optval < 8) || (*(const int*)optval > 0xffff))) {
						/* don't allow illegal values! */
						sock->conn->pcb.udp->chksum_len_rx = 8;
					} else {
						sock->conn->pcb.udp->chksum_len_rx = (u16_t) * (const int*)optval;
					}

					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_UDPLITE, UDPLITE_RECV_CSCOV) -> %d\n",
					                            s, (*(const int*)optval)));
					break;

				default:
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_UDPLITE, UNIMPL: optname=0x%x, ..)\n",
					                            s, optname));
					err = ENOPROTOOPT;
					break;
			}  /* switch (optname) */

			break;
#endif /* LWIP_UDP */

		/* Level: IPPROTO_RAW */
		case IPPROTO_RAW:
			switch(optname) {
#if LWIP_IPV6 && LWIP_RAW

				case IPV6_CHECKSUM:

					/* It should not be possible to disable the checksum generation with ICMPv6
					 * as per RFC 3542 chapter 3.1 */
					if(sock->conn->pcb.raw->protocol == IPPROTO_ICMPV6) {
						return EINVAL;
					}

					LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, int, NETCONN_RAW);

					if(*(const int*)optval < 0) {
						sock->conn->pcb.raw->chksum_reqd = 0;
					} else if(*(const int*)optval & 1) {
						/* Per RFC3542, odd offsets are not allowed */
						return EINVAL;
					} else {
						sock->conn->pcb.raw->chksum_reqd = 1;
						sock->conn->pcb.raw->chksum_offset = (u16_t) * (const int*)optval;
					}

					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_RAW, IPV6_CHECKSUM, ..) -> %d\n",
					                            s, sock->conn->pcb.raw->chksum_reqd));
					break;
#endif /* LWIP_IPV6 && LWIP_RAW */

				default:
					LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_RAW, UNIMPL: optname=0x%x, ..)\n",
					                            s, optname));
					err = ENOPROTOOPT;
					break;
			}  /* switch (optname) */

			break;

		default:
			LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, level=0x%x, UNIMPL: optname=0x%x, ..)\n",
			                            s, level, optname));
			err = ENOPROTOOPT;
			break;
	}  /* switch (level) */

	return err;
}

int
lwip_ioctl(int s, long cmd, void* argp)
{
	struct lwip_sock* sock = get_socket(s);
	u8_t val;
#if LWIP_SO_RCVBUF
	u16_t buflen = 0;
	int recv_avail;
#endif /* LWIP_SO_RCVBUF */

	if(!sock) {
		return -1;
	}

	switch(cmd) {
#if LWIP_SO_RCVBUF || LWIP_FIONREAD_LINUXMODE

		case FIONREAD:
			if(!argp) {
				sock_set_errno(sock, EINVAL);
				return -1;
			}

#if LWIP_FIONREAD_LINUXMODE

			if(NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_TCP) {
				struct pbuf* p;

				if(sock->lastdata) {
					p = ((struct netbuf*)sock->lastdata)->p;
					*((int*)argp) = p->tot_len - sock->lastoffset;
				} else {
					struct netbuf* rxbuf;
					err_t err;

					if(sock->rcvevent <= 0) {
						*((int*)argp) = 0;
					} else {
						err = netconn_recv(sock->conn, &rxbuf);

						if(err != ERR_OK) {
							*((int*)argp) = 0;
						} else {
							sock->lastdata = rxbuf;
							sock->lastoffset = 0;
							*((int*)argp) = rxbuf->p->tot_len;
						}
					}
				}

				return 0;
			}

#endif /* LWIP_FIONREAD_LINUXMODE */

#if LWIP_SO_RCVBUF
			/* we come here if either LWIP_FIONREAD_LINUXMODE==0 or this is a TCP socket */
			SYS_ARCH_GET(sock->conn->recv_avail, recv_avail);

			if(recv_avail < 0) {
				recv_avail = 0;
			}

			*((int*)argp) = recv_avail;

			/* Check if there is data left from the last recv operation. /maq 041215 */
			if(sock->lastdata) {
				struct pbuf* p = (struct pbuf*)sock->lastdata;

				if(NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_TCP) {
					p = ((struct netbuf*)p)->p;
				}

				buflen = p->tot_len;
				buflen -= sock->lastoffset;

				*((int*)argp) += buflen;
			}

			LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_ioctl(%d, FIONREAD, %p) = %"U16_F"\n", s, argp, *((u16_t*)argp)));
			sock_set_errno(sock, 0);
			return 0;
#else /* LWIP_SO_RCVBUF */
			break;
#endif /* LWIP_SO_RCVBUF */
#endif /* LWIP_SO_RCVBUF || LWIP_FIONREAD_LINUXMODE */

		case(long)FIONBIO:
			val = 0;

			if(argp && *(u32_t*)argp) {
				val = 1;
			}

			netconn_set_nonblocking(sock->conn, val);
			LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_ioctl(%d, FIONBIO, %d)\n", s, val));
			sock_set_errno(sock, 0);
			return 0;

		default:
			break;
	} /* switch (cmd) */

	LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_ioctl(%d, UNIMPL: 0x%lx, %p)\n", s, cmd, argp));
	sock_set_errno(sock, ENOSYS); /* not yet implemented */
	return -1;
}

/** A minimal implementation of fcntl.
 * Currently only the commands F_GETFL and F_SETFL are implemented.
 * Only the flag O_NONBLOCK is implemented.
 */
int
lwip_fcntl(int s, int cmd, int val)
{
	struct lwip_sock* sock = get_socket(s);
	int ret = -1;

	if(!sock) {
		return -1;
	}

	switch(cmd) {
		case F_GETFL:
			ret = netconn_is_nonblocking(sock->conn) ? O_NONBLOCK : 0;
			sock_set_errno(sock, 0);
			break;

		case F_SETFL:
			if((val & ~O_NONBLOCK) == 0) {
				/* only O_NONBLOCK, all other bits are zero */
				netconn_set_nonblocking(sock->conn, val & O_NONBLOCK);
				ret = 0;
				sock_set_errno(sock, 0);
			} else {
				sock_set_errno(sock, ENOSYS); /* not yet implemented */
			}

			break;

		default:
			LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_fcntl(%d, UNIMPL: %d, %d)\n", s, cmd, val));
			sock_set_errno(sock, ENOSYS); /* not yet implemented */
			break;
	}

	return ret;
}

#if LWIP_IGMP
/** Register a new IGMP membership. On socket close, the membership is dropped automatically.
 *
 * ATTENTION: this function is called from tcpip_thread (or under CORE_LOCK).
 *
 * @return 1 on success, 0 on failure
 */
static int
lwip_socket_register_membership(int s, const ip4_addr_t* if_addr, const ip4_addr_t* multi_addr)
{
	struct lwip_sock* sock = get_socket(s);
	int i;

	if(!sock) {
		return 0;
	}

	for(i = 0; i < LWIP_SOCKET_MAX_MEMBERSHIPS; i++) {
		if(socket_ipv4_multicast_memberships[i].sock == NULL) {
			socket_ipv4_multicast_memberships[i].sock = sock;
			ip4_addr_copy(socket_ipv4_multicast_memberships[i].if_addr, *if_addr);
			ip4_addr_copy(socket_ipv4_multicast_memberships[i].multi_addr, *multi_addr);
			return 1;
		}
	}

	return 0;
}

/** Unregister a previously registered membership. This prevents dropping the membership
 * on socket close.
 *
 * ATTENTION: this function is called from tcpip_thread (or under CORE_LOCK).
 */
static void
lwip_socket_unregister_membership(int s, const ip4_addr_t* if_addr, const ip4_addr_t* multi_addr)
{
	struct lwip_sock* sock = get_socket(s);
	int i;

	if(!sock) {
		return;
	}

	for(i = 0; i < LWIP_SOCKET_MAX_MEMBERSHIPS; i++) {
		if((socket_ipv4_multicast_memberships[i].sock == sock) &&
		        ip4_addr_cmp(&socket_ipv4_multicast_memberships[i].if_addr, if_addr) &&
		        ip4_addr_cmp(&socket_ipv4_multicast_memberships[i].multi_addr, multi_addr)) {
			socket_ipv4_multicast_memberships[i].sock = NULL;
			ip4_addr_set_zero(&socket_ipv4_multicast_memberships[i].if_addr);
			ip4_addr_set_zero(&socket_ipv4_multicast_memberships[i].multi_addr);
			return;
		}
	}
}

/** Drop all memberships of a socket that were not dropped explicitly via setsockopt.
 *
 * ATTENTION: this function is NOT called from tcpip_thread (or under CORE_LOCK).
 */
static void
lwip_socket_drop_registered_memberships(int s)
{
	struct lwip_sock* sock = get_socket(s);
	int i;

	if(!sock) {
		return;
	}

	for(i = 0; i < LWIP_SOCKET_MAX_MEMBERSHIPS; i++) {
		if(socket_ipv4_multicast_memberships[i].sock == sock) {
			ip_addr_t multi_addr, if_addr;
			ip_addr_copy_from_ip4(multi_addr, socket_ipv4_multicast_memberships[i].multi_addr);
			ip_addr_copy_from_ip4(if_addr, socket_ipv4_multicast_memberships[i].if_addr);
			socket_ipv4_multicast_memberships[i].sock = NULL;
			ip4_addr_set_zero(&socket_ipv4_multicast_memberships[i].if_addr);
			ip4_addr_set_zero(&socket_ipv4_multicast_memberships[i].multi_addr);

			netconn_join_leave_group(sock->conn, &multi_addr, &if_addr, NETCONN_LEAVE);
		}
	}
}
#endif /* LWIP_IGMP */
#endif /* LWIP_SOCKET */
